System and method for electro-optically producing and displaying spectrally-multiplexed images of three-dimensional imagery for use in stereoscopic viewing thereof

ABSTRACT

A Method and apparatus is provided for producing and displaying pairs of spectrally-multiplexed gray-scale or color images of 3-D scenery for use in stereoscopic viewing wherein pairs of spectrally-multiplexed color images of 3-D scenery are produced using a camera system records left and right color perspective images thereof and optically processes the spectral components thereof. In another illustrative embodiment, pairs of spectrally-multiplexed color images of 3-D imagery are produced within a computer-based system which generates left and right perspective images thereof using computer graphic processes, and processes the pixel data thereof using pixel-data processing methods. Thereafter, produced pairs of spectrally-multiplexed images can be recorded on diverse recording mediums, and accessed by the display system for real-time display on diverse display surfaces including, for example, flat-panel liquid-crystal display (LCD) surfaces, CRT display surfaces, projection display screen surfaces, and electro-luminescent panel display surfaces. In the display system, stereoscopic viewing of 3-D imagery is facilitated by wearing electrically passive or electrically-active light polarizing spectacles during the image display process of the present invention.

RELATED CASES

This is a Continuation of application Ser. No. 08/152,020 filed Nov. 12,1993.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for producingand displaying spectrally-multiplexed images of three-dimensionalimagery for use in stereoscopic viewing thereof.

2. Brief Description of the Prior Art

The use of stereoscopic imaging in modern times has gained increasingpopularity. The reason for this trend in technological innovation isquite clear. At birth, each human being is endowed with the power ofstereoscopic vision, and it is this power alone that enables humanbeings to view the world and all its inhabitants in three dimensionswith full depth perception.

Presently, there exist a number of known techniques for recording anddisplaying stereoscopic images of three dimensional objects and scenery.In the art of video imaging, in particular, two principally differenttechniques are presently being used to record and display stereoscopicimages. The first technique is commonly referred to as"time-multiplexed" or "field-sequential" stereo video or television,whereas the second technique is commonly referred to as "spatiallymultiplexed" stereo video or television.

In general, each of these stereo imaging techniques involve imagerecording (i.e. generation) and image display processes. During theimage generation process, left and right perspective images (orsequences of perspective images) of 3-D scenery are produced andsubsequently recorded on a suitable recording medium. Notably, therecorded left and right perspective images are produced as if actuallyviewed with the inter-pupil distance of a human observer. Then, duringthe image display process, the visible light associated with the leftand right perspective images is visually presented to the left and righteyes of viewers, respectively, while minimizing the amount of visiblelight from the left and right perspective images that impinge upon theright and left eyes of the viewer, respectively. As the left and rightperspective images of the 3-D scenery are viewed by the left and righteyes of the viewer, a stereoscopic image of the 3-D scenery isperceived, complete with full spatial and depth information of theactual 3-D scenery.

The differences between the above described techniques reside in themanner in which left and right perspective images are "channeled" to theleft and right eyes of the viewer in order to preserve stereoscopy.These techniques will be briefly described below.

In 3-D video display systems based upon time-multiplexing principles theleft and right perspective images of the 3-D scenery are displayed toviewers during different display periods (i.e. left and rightperspective display periods). To ensure that only left perspectiveimages of the 3-D scenery are presented to the left eyes of viewers, theright eye of each viewer is not allowed to view the left perspectiveimage during the left perspective image display period. Similarly, toensure that only the right perspective images of the 3-D scenery arepresented to the right eyes of viewers, the left eye of each viewer isnot allowed to view the right perspective image during the rightperspective image display period. In the contemporary period, thisperspective image "blocking" or selective viewing process is achievedusing a pair of liquid crystal light valves(LCLV) as the lenses inspecial eye wear (e.g. goggles ) worn by each viewer using a 3-D imageviewing system based on such principles. Typically, a controller isrequired in order to drive the left LCLV lens during each leftperspective image display period, and drive the right LCLV lens duringeach right perspective image display period.

In 3-D video display systems based upon spatial-multiplexing principles,left and right perspective images of 3-D scenery are spatiallymultiplexed during the image generation process in order to produce aspatially multiplexed composite image. Then during the image displayprocess, the visible light associated with the left and rightperspective image components of the composite image are simultaneouslydisplayed, but with spatially different "polarizations" impartedthereto. To ensure that only left perspective images of the 3-D sceneryare presented to the left eyes of viewers, the right eye of each viewermust not be allowed to view left perspective images. Similarly, toensure that only the right perspective images of the 3-D scenery arepresented to the right eyes of viewers, the left eye of each viewer mustnot be allowed to view right perspective images. Typically, thisperspective image "blocking" or selective-viewing process is achievedusing a pair of spatially different polarizing lenses mounted in eyewear (e.g. spectacles) worn by each viewer using a 3-D video displaysystem based on such principles of operation.

While each of these above-described 3-D image display techniques may beused to display 3-D color or gray-scale images, systems based on suchtechniques are not without shortcomings and drawbacks.

In particular, 3-D image display systems based upon time-multiplexingprinciples are notoriously plagued by "image flicker" problems. While3-D video display systems based upon spatial-multiplexing principles areinherently free from the "image flicker" problem associated withtime-multiplexed 3-D display systems, spatial-multiplexed 3-D displaysystems require the use of micropolarizers mounted onto display surfaces(e.g. CRT displays, flat panel liquid-crystal displays, light valveprojectors, etc.) from which the polarized light ofspatially-multiplexed images emanates. Consequently, this requirementnecessitates specially manufactured display and projection surfaceswhich, in particular applications, can impose undesirable limitationsupon the stereoscopic viewing process.

As an alternative to the above-described 3-D image display systems andmethods, U.S. Pat. No. 4,995,718 to Jachimowicz, et al. proposes a 3-Dcolor video projection display system using spectral-multiplexing andlight polarization principles. Similar to the above-described 3-D imagedisplay systems, the proposed 3-D projection display system in U.S. Pat.No 4.995,718 supports both image recording(i.e. generation) and displayprocesses. However, unlike 3-D image display systems based upontime-multiplexing and spatial-multiplexing principles described above,the 3-D color projection display system of U.S. Pat. No. 4,995,718exploits the spectral properties of both left and right perspectivecolor images in order to ensure that only left and right perspectivecolor images of a 3-D scenery are seen by the left and right eyes ofviewers , respectively, during the image display process. Specifically,during the image generation process, left and right perspective colorvideo images of 3-D scenery are recorded. Then during a first displayperiod in the image projection process, the red and blue spectralcomponents (i.e. magenta) of the left perspective color image areimparted with a first light polarization state and then projected onto adisplay screen using a first image projector, while the green spectralcomponents of the right perspective color image are imparted with asecond light polarization state and projected onto the display screenusing a second image projector. During the image projection process ofthe first display period, the separately projected left and rightperspective images must be spatially superimposed (i.e., aligned) inorder that these differently polarized spectral components arerecombined or "multiplexed" on the projection display screen, which isadapted to preserve the polarization states of the multiplexed spectralcomponents. To ensure that only the magenta spectral components of theleft perspective image are presented to the left eyes of viewers duringthe first display period, while only the green spectral components ofthe right perspective image are presented to the right eyes of viewers,the viewers are each required to wear spectacles having a left lenscharacterized by the first polarization state, and a right lenscharacterized by the second polarization state.

Then during a second display period in the image projection process, thegreen spectral components of the left perspective color image areimparted with a first light polarization state and then projected ontothe display screen using the first image projector, while the magentaspectral components of the right perspective color image are impartedwith a second light polarization state and then projected onto thedisplay screen using the second image projector. During the seconddisplay period the separately projected left and right perspectiveimages must be spatially superimposed (i.e., aligned) in order thatthese differently polarized spectral components are recombined (i.e.multiplexed) on the projection display screen. Also, the polarizedspectacles worn by each viewer ensures that only the green spectralcomponents of the left perspective image are visually presented to theleft eyes of viewers during the first display period, while only themagenta spectral components of the right perspective image are visuallypresented to the right eyes of the viewers. As the projected spectrallymultiplexed images are viewed by the viewers wearing the polarizedspectacles during the first and second display periods , a stereoscopicimage of the 3-D scenery is perceived, complete with full spatial anddepth information of the actual 3-D scenery.

While the 3-D color projection display system disclosed in U.S. Pat. No.4,995,718 is capable of displaying 3-D stereoscopic color images of 3-Dscenery, objects and the like, this prior art system and stereoscopicdisplay technique suffers from several significant shortcomings anddrawbacks.

In particular, this prior art approach requires the use of three imageprojectors in order to project spectrally-filtered, polarized left andright images onto a display screen, upon which the polarized spectralcomponents must recombine during each display period. Such imageprojection operations require multiple image projectors, a displayscreen, a large display viewing area, and complicated optical signalprocessing equipment detailed in the Specification of U.S. Pat. No.4,995,718.

The method of recording and processing left and right color imagesrequired by this prior art stereoscopic display method is generallyincompatible with conventional television transmission and distributionschemes.

Moreover, when using this prior art display technique 3-D stereoscopicimages cannot be "directly" viewed from CRT display surfaces, flat paneldisplay surfaces, LCD display surfaces, plasma display panel surfaces,electroluminescent panel display surfaces and the like.

Thus, there is a great need in the art for an improved method and systemfor generating and displaying gray-scaled or color stereoscopic imagesof 3-D objects, while avoiding the shortcomings and drawbacks of priorart apparatus and methodologies.

OBJECTS AND SUMMARY OF THE PRESENT INVENTION

Accordingly, it is a primary object of the present invention to providea method and apparatus for producing stereo images of 3-D objects andscenery, while overcoming the shortcomings and drawbacks of prior artmethodologies and apparatus.

A further object of the present invention is to provide a method andsystem for producing and displaying spectrally-multiplexed color imagesof 3-D scenery for use in stereoscopic viewing thereof.

A further object of the present invention is to provide a method ofproducing a pair of spectrally-multiplexed color images of 3-D sceneryby recording left and right color perspective images and thereafterprocessing the spectral components thereof.

A further object of the present invention is to provide such a methodand system for producing pairs of spatially-multiplexed composite imagesof 3-D imagery, wherein the spectral components of spatiallycorresponding pixels in the left and right perspective images aremultiplexed (i.e. combined) on a pixel-by-pixel basis in order toproduce the pixels in each of the spatially-multiplexed compositeimages, prior to sequentially displaying the same to viewers.

A further object of the present invention is to provide a method andsystem for direct stereoscopic viewing of 3-D imagery using pairs ofspectrally-multiplexed composite images produced by the method andsystem described above.

A further object of the present invention is to provide a method ofproducing spectrally-multiplexed color images of 3-D scenery, from adiverse array of devices, including computer systems, camera systems,laser-disc playback units, video-tape recording and playback units,color image scanners, television signal receivers and the like.

A further object of the present invention is to provide anelectro-optical device for multiplexing selected spectral components inperspective color images of 3-D scenery, during the production ofspectrally-multiplexed color images(SMCI) thereof.

A further object of the present invention is to provide a system andmethod for displaying pairs of spectrally-multiplexed color images of3-D scenery in order to permit color stereoscopic viewing thereof.

A further object of the present invention is to provide a method andapparatus for displaying spectrally-multiplexed color images of 3-Dscenery on diverse display surfaces including CRT display surfaces,flat-panel liquid-crystal display (LCD) surfaces, electro-luminescentpanel display surfaces, projection screen surfaces, and other displaysurfaces capable of displaying gray-scale or color images at video framedisplay rates greater than or equal to the flicker frequency of thehuman vision system.

A further object of the present invention is to embody such a method andapparatus within conventional desktop, laptop, and notebook computersystems in order to provide full 3-D color display capabilities to usersthereof.

An even further object of the present invention is to provide a portablecomputer system capable of displaying pairs of spectrally-multiplexedcolor images of 3-D scenery in order to permit color stereoscopicviewing thereof while wearing a pair of electrically passive orelectrically-active polarized spectacles during the display process.

A further object of the present invention is to provide such a colorstereoscopic display system and method, in which stereoscopic viewing of3-D scenery is achievable while wearing a pair of electrically-passivepolarized spectacles during the display process.

A further object of the present invention is to provide such a colorstereoscopic display system and method, in which viewing of 3-D sceneryis achievable while wearing a pair of electrically-active polarizedspectacles during the display process.

An even further object of the present invention is to provide a anelectro-optical device for use in polarizing selected spectralcomponents in spectrally-multiplexed color images of 3-D scenery duringthe stereoscopic display thereof.

A further object of the present invention is to provide a method of andsystem for recording and displaying spectrally-multiplexed color imagesof 3-D scenery, which can be readily utilized in conventional televisiontransmission and distribution systems, such as cable television systemsand networks, without substantial modification to the same.

These and other objects of the present invention will become apparenthereinafter and in the Claims to Invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, the DetailedDescription of the Illustrative Embodiments of the Present Invention isto be read in conjunction with the following drawings, in which:

FIG. 1 is a block schematic diagram of the apparatus for producing anddisplaying spectrally-multiplexed color images (SMCI) of 3-D scenery foruse in stereoscopic viewing thereof in accordance with the presentinvention;

FIG. 2 is a block schematic diagram of a generic device for producingspectrally-multiplexed color images of 3-D scenery from pairs of leftand right perspective color images thereof;

FIG. 3 is a block schematic diagram of a computer system programmed inaccordance with the principles of the present invention and capable ofproducing pairs of spectrally-multiplexed color images of 3-D sceneryfrom pairs of left and right perspective color images thereof;

FIGS. 3A to 3D provide a schematic representation of the pixel-dataprocessing method carried out by the computer system of FIG. 3 in orderto produce pairs of spectrally-multiplexed color images of 3-D sceneryfrom pairs of left and right perspective color images thereof;

FIG. 4 is a schematic block diagram of a first embodiment of the camerasystem of the present invention which produces spectrally-multiplexedcolor images of 3-D scenery from pairs of left and right perspectivecolor images thereof;

FIG. 4A is a perspective view of a generic optical-image spectrummultiplexer (OISM) in accordance with the present invention;

FIGS. 4B and 4C, taken together, show a flow chart illustrating anoptical image processing method carried out by the camera system of FIG.4 in order to produce pairs of spectrally-multiplexed color images frompairs of left and right perspective color images thereof;

FIG. 5A is a detailed schematic diagram showing an exploded view of afirst illustrative embodiment of the optical-image spectrum multiplexershown in FIG. 4A;

FIG. 5B is a perspective view of the optical image spectrum multiplexerof the present invention, shown fully assembled;

FIG. 5C is a schematic representation illustrating the magnitude versuswavelength response characteristics of an exemplary optical image havingmultiple groups of spectral components, which are provided to the inputsurface of the optical image spectrum multiplexer shown in FIG. 5A;

FIG. 5D is a schematic representation illustrating the magnitude versuswavelength response characteristics of the optical image emerging fromthe output surface of the optical image spectrum multiplexer shown inFIG. 5A, when the control voltage provided thereto has a first prespecified value;

FIG. 5E is a schematic representation illustrating the magnitude versuswavelength response characteristics of the optical image emerging fromthe output surface of the optical image spectrum multiplexer shown inFIG. 5A, when the control voltage provided thereto has a second prespecified value;

FIG. 5F is a particular embodiment of the optical-image spectrummultiplexer of the present invention shown in FIG. 5A, particularlyadapted for multiplexing the spectral component groups associated withthe colors green, red and blue;

FIG. 5G is a schematic representation illustrating the transmissionversus wavelength response characteristics of an exemplary optical imageprovided to the input surface of the optical image spectrum multiplexershown in FIG. 5F;

FIG. 5H is a schematic representation illustrating the transmissionversus wavelength response characteristics of the optical image emergingfrom the output surface of the optical image spectrum multiplexer shownin FIG. 5E, when the control voltage provided thereto has a first value

FIG. 5I is a schematic representation illustrating the transmissionversus wavelength response characteristics of the optical image emergingfrom the output surface of the optical image spectrum multiplexer shownin FIG. 5, when the control voltage provided thereto has a second value;

FIGS. 6A and 6B are schematic representations of a first illustrativeembodiment of the solid-state camera system of the present invention,employing a pair of optical-image spectrum multiplexers of the typeshown in FIG. 5C in order to produce a pair of spectrally-multiplexedcolor images of 3-D scenery from two pairs of left and right perspectiveimages thereof;

FIG. 6C is a table illustrating which spectral components aremultiplexed, optically combined, and subsequently recorded during thealternating recording periods of the image recording process carried outby the camera system of the present invention shown in FIGS. 6A and 6B;

FIG. 7A is a schematic block diagram of a second illustrative embodimentof the solid-state camera system of the present invention, employingdigital signal processing in order to produce a pair a pair ofspectrally-multiplexed color images of 3-D scenery from a single pair ofleft and right perspective color images thereof;

FIGS. 7B through 7E, taken together, provide a schematic representationof a digital image processing method carried out by the camera systemshown in FIG. 7A in order to produce a pair of spectrally-multiplexedcolor images of 3-D scenery from a single pair of left and rightperspective images thereof;

FIGS. 8A and 8B, taken together, provide a schematic representation of asystem and method for displaying a pair of spectrally-multiplexed colorimages of 3-D scenery, stereoscopically viewable through a pair ofelectrically-active polarized lenses, each incorporating either theoptical-image spectrum polarizer of the present invention shown in FIGS.9A or 9C;

FIG. 9A is an exploded schematic diagram of a first embodiment of theoptical-image spectrum polarizer of the present invention employed inthe display system of FIGS. 8A and 8B, and particularly adapted toimpart one of two possible polarization states to the multiple spectralcomponent groups present in the spectrally-multiplexed color imagesbeing displayed;

FIG. 9B is a schematic representation illustrating the magnitude versuswavelength response characteristics of an exemplary optical image ofarbitrary spectral intensity, provided to the input surface of theoptical image spectrum polarizer shown in FIG. 9A;

FIGS. 9C and 9D are schematic representations illustrating thepolarization versus wavelength response characteristics of theoptical-image spectrum polarizer shown in FIG. 9A during the first andsecond cyclical display periods of the stereoscopic image displayprocess of the present invention;

FIG. 9E is an exploded schematic diagram of a second illustrativeembodiment of the optical-image spectrum polarizer of the presentinvention, particularly adapted to impart one of two possiblepolarization states to the spectral component groups associated with thecolors green, red and blue typically present in spectrally-multiplexedcolor images being displayed;

FIG. 9F is a schematic representation illustrating the polarizationversus wavelength response characteristics of an exemplary color opticalimage provided to the input surface of the optical image spectrumpolarizer shown in FIG. 9E;

FIGS. 9G to 9I are schematic representations illustrating thepolarization versus wavelength response characteristics of theoptical-image spectrum polarizer shown in FIG. 9E, exhibited during thefirst and second cyclical display periods of the image display processof the present invention;

FIG. 10A is a schematic representation of a system adapted for receivinga pair of spectrally-multiplexed color images of 3-D scenery from aselected SCMI generating device of the present invention, and fordisplaying the same so that the 3-D imagery is stereoscopically viewablethrough a pair of electrically-active polarized spectacles worn by theviewer;

FIG. 10B is a table illustrating which spectral components are displayedby the system of FIG. 10A during the cyclical display periods of thespectral-polarizing display process of the present invention;

FIG. 10C is a perspective view of an electrically-active pair ofpolarizing spectacles constructed in accordance with the presentinvention;

FIG. 11A is a schematic representation of a projection-type system fordisplaying a pair of spectrally-multiplexed color images of 3-D scenery,stereoscopically viewable through a pair of electrically-active,radio-frequency linked, polarized lenses worn by the viewer andembodying the optical-image spectrum polarizers shown in FIG. 9E;

FIG. 11B is a table illustrating which spectral components are displayedby the system of FIG. 11A during the cyclical display periods of theimage display process of the present invention;

FIGS. 12A and 12B, taken together, provide a schematic representation ofa method and system for displaying pairs of spectrally-multiplexed colorimages of 3-D scenery, stereoscopically viewable through a pair ofelectrically-passive polarized spectacles worn by the viewer;

FIG. 12C is a table illustrating which spectral components are displayedby the system of FIGS. 12A and 12B during the cyclical display periodsof the image display process of the present invention;

FIG. 13A is a schematic representation of an LCLV type projection systemfor displaying a pair of spectrally-multiplexed color images of 3-Dscenery, stereoscopically viewable through a pair ofelectrically-passive polarized lenses worn by the viewer;

FIG. 13B is a table illustrating which spectral components are displayedby the system of FIG. 13A during the cyclical display periods of thespectral-polarizing display process of the present invention;

FIG. 14A is a perspective diagram of a portable computer having a colorstereoscopic display system constructed in accordance with theprinciples of the present invention;

FIG. 14B is a block diagram of the portable computer shown in FIG. 14A;

FIG. 15 is a table illustrating the magnitude values for the spectralcomponent groups of exemplary left and right perspective color imageswhich, when processed to produce spectrally-multiplexed color images,may result in potential image-flicker during stereoscopic viewingthereof;

FIGS. 16A and 16B are schematic representations illustrating thepixel-data processing operations performed during a modified method ofproducing spectrally-multiplexed color images according to the presentinvention, such that the potential of image-flicker is eliminated duringthe stereoscopic viewing process of the present invention

FIGS. 17A to 17G, taken together, provide a flow chart illustrating thesteps performed during the modified method of producingspectrally-multiplexed color images according to the present invention;

FIG. 18 is a block schematic diagram of a 3-D color television signaltransmission and distribution system constructed in accordance with theprinciples of the present invention;

FIG. 19 is schematic diagram illustrating a conventional colortelevision system adapted with the spectral polarization panel of thepresent invention and interconnected with a cable television signalreceiving device within the 3-D color television signal transmission anddistribution of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS OF THE PRESENTINVENTION

As illustrated in FIG. 1, the present invention embraces both theproduction and display of spectrally-multiplexed images of 3-D imagerywhich permit viewers to stereoscopically view the same with theperceptionof full depth and three dimensionality. As used hereinafterand in the claims to invention appended hereto, the term "3-D imagery","3-D scenery", and "3-D object" shall be understood to include any formof imagery, real or synthetic, concrete or abstract, having structural,graphical or ornamental features representable within three or moredimensions, which may include, but certainly is not limited to,three-dimensional physical space in which the spatial dimensionality ofobject are conventionally represented. Also, as used hereinafter and inthe claims to invention, the term "spectrally-multiplexed" and"spectral-multiplexing" shall be understood to include the selectivecombining of spectral components of two or more perspective opticalimagesof 3-D scenery, as well as the selective combining of pixel colorvalues (i.e. codes) of perspective image data.

While the present invention can be used to produce and display eithercoloror gray-scaled spectrally-multiplexed images of 3-D scenery, theillustrative embodiments of the present invention shall be describedhereinafter using color perspective images, although it shall beunderstood that gray-scaled (e.g. black and white) perspective imagescan be utilized with excellent results to produce and displayspectrally-multiplexed gray-scaled images of 3-D scenery

In general, spectrally-multiplexed color images (SMCI) can be producedusing a spectrally-multiplexed color image producing camera system 1, aSMCI producing computer system 2, or any other SMCI producing device 4constructed and operated in accordance with the principles of thepresent invention. Such apparatus and processes will be described ingreat detail with reference to FIGS. 2 through 7E. Similarly,spectrally-multiplexed gray-scaled and color images can bestereoscopically displayed using a number of different type displaysystems constructed and operated in accordance with the principles ofthe present invention. Such display systems are generally represented bythe block designated by reference numeral 3 in FIG. 1. Such apparatusand processes will be described in great detail hereinafter withreference to FIGS. 8A through 14B.

In FIG. 2, a spectrally-multiplexed image generator 4 is schematicallyillustrated. In accordance with the present invention, pairs ofspectrally-multiplexed color images, I_(SMCT) (1,k) and I_(SMCI)(2,k),are sequentially displayed at a video frame display rate in excessof the flicker frequency (e.g., 30 frames per second) in order to enablea viewerto perceive 3-D scenery with full three dimensionality and depthperception, along a particular point of view. As shown, each suchspectrally-multiplexed color image displayed contains a selected groupof spectral components (e.g. red and blue color related spectralcomponents or green color related spectral components) taken from theleft and right perspective color images I_(L) and I_(R) of the 3-Dscene. As will be described in great detail hereinafter, the spectralmultiplexing process carried out by the SMCI generator 4 can be realizedwithin a computer system using the pixel data processing techniquesillustrated in FIGS. 3 and 3A, and 7A and 7B, or by optical processingtechniques carried out by the camera systems illustrated in FIGS. 4through 7D.

As illustrated in FIG. 3, the SMCI computer system (e.g. workstation) 5of the illustrative embodiment comprises a number of integrated systemcomponents, namely: one or more central processing units 6 (e.g.microprocessor); program memory storage 7 for storing an operatingsystem program, application programs, and various image processingroutines of the present invention; random access data storage memory(e.g. VRAM) 8 forstoring left and right color perspective images of a3-D object or scene, upon which spectral multiplexing is to beperformed; a mass-type data storage memory 9 for storing produced pairsof spectrally-multiplexed color images {I_(SMCI) (1,k), I_(SMCI) (2,k)};a visual display unit 10 having a visual display screen or surface; akeyboard or other text input device 11; a pointing and selecting device(e.g. mouse or track-ball) 12; and one or more video output devices 13,such as CD-ROM orstereo-video camera. As illustrated, each of thesesystem components is operably associated with processor 6 by way of oneor more system buses 14in a manner known in the art. In the preferredembodiment, the operating system may be Unix® X-Windows, allowing theprocessor to support at least two input/output windows, pointing andselecting device 12, and multi-media input and output devices 13. It isunderstood, however, that other suitable operating system programs canbe used with acceptable results. In applications where images of 3-Dscenery or objects are generated using computer programming techniques,conventional computational algorithms can be used to generated left andright color perspective images with the computer system. Presentlysuitable graphics software is commercially available for creating highresolution 3-D color models, renderings and animations, as well asperforming perspective imagegeneration functions upon Intel 386/486microprocessor based personal computer systems. Exemplary software isavailable from Autodesk, Inc. of Sausalito, Calif. under the trademark"Autodesk 3D Studio," Release 2.

In general, each such perspective color image produced within the SMCIcomputer system comprises a matrix of pixels. Each pixel in the imagematrix is designated as P(x_(i), y_(j))=({x_(i), y_(j) }, {r_(i), j },{g_(i),j }, {b_(i),j }), and has a color value representative of thespectral content of the image at the pixel's location in the image,indicated by the coordinate pair (x,y). In typical color videoapplications, the color value of each pixel contains a magnitude foreach of the spectral components, e.g. {g_(i),j }, {b_(i),j }, {r_(i),j}, constituting the system of color representation being used in theillustrative embodiment. In the SMCI computer system of the presentinvention, the left and right color perspective images are stored indata storage memory (e.g. frame buffers) 7 and are then processed byprocessor 6 in accordance with the spectral-multiplexing algorithmschematically illustrated in FIG. 3A. As shown, thespectral-multiplexing algorithm comprises six stages of data processingwhich together produce pairs of spectrally-multiplexed color images fordisplay and stereoscopically viewing of the 3-D object modeled in thecomputer system. To achieve computational efficiency, these stages canbe performed simultaneously (e.g., in parallel) as shown.

As illustrated at Block A in FIG. 3A, processor 6 performs the firststep in the first stage of the spectral-multiplexing algorithm byaccessing from data storage memory 8, a frame of digital datarepresentative of the left perspective color image I_(L) where eachpixel therein is designated as :P(x_(i), y_(j))=({x_(i), y_(j) },{r_(i),j }, {g_(i),j }, {b_(i),j }), and i=0,1, . . . N-1 and j=0,1, . .. , M-1. At Block B, for each pixel P_(L) (x_(i), y_(j)) in the leftcolor perspective image I_(L), the processor selects the color value(i.e. color codes) associated with the first predefined spectralcomponent groupSCG1 (i.e. {r}, {b}). Then at Block C the processorwrites the selected pixel color value to the corresponding pixellocation in a first image buffer set up in data storage memory 8. Whenthe processor determines at Block D that the last pixel in the leftperspective image has been processed(i.e. i=N-1 and j=M-1), it proceedsto Block E. While the pixel-data processing operations set forth atBlocks A through D are beingcarried, preferably the corresponding imageprocessing operations set forthat Blocks A' through D' are carried outin parallel using a second image buffer. For purposes of completion,these pixel-data processing operationswill be described below.

As illustrated at Block A' in FIG. 3C, the first step in the secondstage of the spectral-multiplexing algorithm involves accessing fromdata storage memory 8, a frame of digital data representative of theright perspective color image I_(R) where each pixel therein isdesignated as:P(x_(i), y_(j))=({x_(i),y_(j) }, {r_(i),j }, {g_(i),j },{b_(i),j }), and i=0,1, . . . N-1 and j=0,1, . . . , M-1. At Block B',for each pixel P_(R) (x_(i),y_(j))) in the right color perspective imageI_(R), the processor selects the color value (i.e. color code)associated with the second predefined spectral component group SCG2(i.e. {g}). Then at Block B' the processor writes the selected pixelcolor valueto the corresponding pixel location in a second image bufferset up in datastorage memory 8. When the processor determines at BlockD' that the last pixel in the right perspective image has been processed(i.e. i=N-1 and j=M-1), the processor proceeds to Block E' in FIG. 3D.

At Block E in FIG. 3B, the processor processes the spectrally filteredimages residing in the first and second image buffers so as to produce afirst spectrally-multiplexed color image I_(SMCI) (1,k). As indicatedatBlock E, for each pair of spatially corresponding pixels in the pairof spectrally filtered images buffered in the first and second imagebuffers,the processor adds together the corresponding color values{r_(x),y }, {g_(x),k }, {b_(x),y } in order to yield the (i,j)-thespectrally-multiplexed pixel P_(SMCI) (X_(i), y_(j)) in the firstspectrally-multiplexed color image I_(SMCI) (1,k). in the k-th stereoimage pair thereof. Then at Block F, the processor writes thespectrally-multiplexed pixel P_(SMCI) (x_(i), y_(j)) into its spatiallycorresponding pixel location in a third image buffer set up in datastorage memory 8. As indicated at Block G, these pixel processingoperations are performed for each set of spatially corresponding pixelsresiding in the first and second image buffers, until the entire firstspectrally-multiplexed color image L_(SMCI) (1,k). is generated (i.e.,i=N-1 and j=M-1). Then at Block H, the first spectrally-multiplexedcolor image I_(SMCI) (1,k). is stored in a first image buffer set up indata storage memory 9. Thereafter, the processor proceeds to performpixel-dataprocessing operations necessary to produce the secondspectrally-multiplexed color image L_(SMCI) (2,k) of the k-th stereoimage pair thereof. The details of these pixel-data processing stageswillbe described below.

As illustrated at Block I in FIG. 3C, the first step in the fourth stageofthe spectral-multiplexing algorithm involves accessing once again fromdatastorage memory 8, the frame of digital data representative of theleft perspective color image I_(L) where each pixel therein isdesignated as : P(x_(i), y_(j))=({x_(i), y_(j) }, {r_(i),j }, {g_(i),j}, {b_(i),j }), and i=0,1, . . . N-1 and j=0,1, . . . , M-1. At Block J,for each pixel P_(L) (x_(i),y_(j)) in the left color perspective imageIL,the processor selects the color value (i.e. color code) associatedwith the second predefined spectral component group SCG2 (i.e. {g}).Then at Block K the processor writes the selected pixel color value tothe corresponding pixel location in a fourth image buffer set up in datastorage memory 8. When the processor determines at Block L that the lastpixel in the left perspective image has been processed (i.e. i=N-1 andj=M-1), the processor performs the pixel-data processing operations setforth at Blocks M through P. Preferably while the processor is carryingout the pixel-data processing operations set forth at Blocks I throughL, it also carries out in parallel corresponding operations at Blocks I'through L'. For purposes of completion, these pixel-data processingoperations will be described below.

As illustrated at Block I' in FIG. 3C, the first step in the fifth stageofthe spectral-multiplexing algorithm involves accessing once again fromdatastorage memory 8, the frame of digital data representative of theright perspective color image I_(R) where each pixel therein isdesignated as : P(x_(i), y_(j))=({x_(i), y_(j) }, {r_(i),j }, {g_(i),j}, {b_(i),j }), and i=0,1, . . .N-1 and j=0,1, . . . , M-1. At Block J',for each pixel P_(R) (X_(i),y_(j)) in the right color perspective imageI_(R), the processor selects the color value (i.e. color codes)associated with the first predefined spectral component group SCG1 (i.e.{r}, {b}). Then at Block K' the processor writes the selected pixelcolor value to the corresponding pixel location in a fifth image bufferset up in data storage memory 8. When the processor determines at BlockP' that the last pixel in the right perspective image has been processed(i.e. i=N-1 and j=M-1), the processor proceeds to Block M in FIG. 3D.

At Block M in FIG. 3D, the processor processes the spectrally filteredimages residing in the fourth and fifth image buffers so as to producethesecond spectrally-multiplexed color image I_(SMCI) (2,k). Asindicated atBlock M, for each pair of spatially corresponding pixels inthe pair of spectrally filtered images buffered in the fourth and fourthimage buffers, the processor adds together the corresponding color codes{r_(x),y }, {g_(x),k }, {b_(x),y } in order to yield the (i,j)-thspectrally-multiplexed pixel P_(SMCI) (x_(i), y_(j)) in the secondspectrally-multiplexed color image I_(SMCI) (2,k). in the k-th stereoimage pair thereof. Then at Block N the processor writes thespectrally-multiplexed pixel P_(SMCI) (x_(i), y_(i)) into its spatiallycorresponding pixel location in a sixth image buffer set up in datastorage memory 8. As indicated at Block O, these pixel-data processingoperations are performed for each set of spatially corresponding pixelsresiding in the fourth and fifth image buffers until the entire secondspectrally-multiplexed color image I_(SMCI) (2,k). is generated . Thenat Block P, the second spectrally-multiplexed color imageI_(SMCI) (2,k).is stored in a second image buffer set up in data storagememory 9 alongwith the first spectrally-multiplexed color image I_(SMCI)(1,k). forfuture access and display. Together, the first and secondspectrally-multiplexed color images comprise a spectrally-multiplexedcolor image pair {I_(SMCI) (1,k),I_(SMCI) (2,k)}, containing sufficientvisual information for stereoscopic viewing of the original 3-Dscene orobject modeled in the computer system. The above-described dataprocessing method can be repeated upon left and right perspective colorimages of either real or synthetic 3-D scenery and objects in order toproduce spectrally-multiplexed color image pairs at a sufficiently highrate to support 3-D stereoscopic display and animation processes. Noveltechniques for stereoscopically displaying pairs ofspectrally-multiplexedcolor images produced by the SMCI computer systemhereof, will be describedin detail hereinafter.

Notably, each pixel in the spectrally-multiplexed image containsspectral component information regarding both left and right perspectiveimages, and these combined spectral components are simultaneouslypresented duringthe stereoscopic display process of the presentinvention. In marked contrast, in prior art spatially-multiplexedcomposite images, spatially corresponding left and right pixels arespatially separated and presented simultaneously during the displayprocess. Furthermore, in prior art time-multiplexed imaging techniques,all of the pixels in the left perspective image and all of the pixels inthe right perspective image aredisplayed sequentially during differentdisplay periods. Consequently, the stereoscopic display imagingtechnique of the present invention can be used in direct stereoscopicviewing applications without suffering from (i) image-flicker commonlyassociated with prior art time-multiplexing techniques or (ii) the lossof image resolution associated with prior art spatial-multiplexingtechniques. In addition, the present invention avoidsthe shortcomingsand drawbacks of prior art spectral-multiplexing techniques of U.S. Pat.No. 4,995,718 by providing general-purpose "directviewing" capabilitiesfor use with CRT, flat panel, electroluminescent and plasma displaysurfaces, as well as all projection display techniques.

In FIG. 4, the first embodiment of the SMCI camera system of the presentinvention is schematically illustrated. Unlike the SMCI computer systemofthe present invention, SMCI camera system 15 utilizes opticalprocessing techniques in order to produce pairs ofspectrally-multiplexed color images of 3-D scenery, from left and rightperspective color images thereof. As shown in FIG. 4, SMCI producingcamera system 15 comprises a number of components, namely: first andsecond color image producing elements 16A and 16B, for producing leftand right perspective color images I_(L) and I_(R), respectively; anoptical image combining element 17 for spatially combining pairs ofoptical images; a color image recording element (e.g., a CCD color imagedetecting array and scanning electronics) 18 and an image frame buffer19 for detecting and recording gray-scaled or color images formed on theimage detecting array; first andsecond optical-image spectrummultiplexers 20A and 20B for selectively multiplexing (i.e.transmitting) groups of spectral components from the left and rightperspective color images, to optical combining element 17; and an imagerecording controller 21 for providing control signals to the first andsecond optical-image spectrum multiplexers 20A and 20B., and also to thecolor image detector 18 in order to control the operation thereof ashereinafter described. The function of optical image combining element17 is to assemble multiplexed spectral components in order to formafirst spectrally-multiplexed color image during a first recordingperiod,and also to assemble multiplexed spectral components in order toform a second spectrally-multiplexed color image during a secondrecording period. The function of recording controller 21 is to generateappropriatecontrol signals which cause the first and secondoptical-image spectrum multiplexers 20A and 20B to selectively transmitparticular groups of spectral components constituting the left and rightperspective images in order to produce (i) the firstspectrally-multiplexed color image on the color-image recording elementduring the first recording period, and (ii) the secondspectrally-multiplexed color image on the color-image detector duringthe second recording period.

In FIG. 4A, optical image spectrum multiplexer 20A, 20B of the presentinvention is schematically represented as an electro-optical element ofphysically thin dimensions (e.g. 1 to 10 millimeters) having anoptically transparent input surface 23 through which the spectralcomponents of a perspective color or perspective gray-scale image arepermitted to enter, and an optically transparent output surface 24 fromwhich selected spectral components of the image are permitted emergeaccording to the control signals generated by the recording controller21 during the image recording process. As schematically illustrated,each perspective color image presented to the input surface of theoptical-image spectrum multiplexer, comprises an ensemble ofelectromagnetic waves of varying wavelength (i.e. frequency) in theoptical region of the electromagnetic spectrum. Typically, perspective"gray-scale" images transmit or reflect electromagnetic energy having abandwidth which extends over the entire optical spectrum, e.g., fromabout 400 to about 750 nanometers. It is understood, however, that thebandwidth characteristics of particular gray-scaled images will varydepending on the spatial characteristics of the scene representedthereby. Perspective "color" images also transmit orreflectelectromagnetic energy having a bandwidth which extends over the entireoptical spectrum, e.g., from about 400 to about 750 nanometers. However,it is understood that the bandwidth characteristics of particularcolorimages may extend into the ultraviolet and/or infrared regions oftheelectromagnetic spectrum. As is well known that certain groups ofoptical wavelengths contribute to the perception of particular colors inthe humanvision system. For example, the color green is perceived whenthe retinal surface of the human vision system is illuminated with thegroup of optical wavelengths in the region characterized by{λ_(G),Δλ_(G) }. The color red is perceived when the retinal surface ofthe human vision system is illuminated with the group of opticalwavelengths in the region characterized by {λ_(R), Δλ_(R) }. Similarly,the color blue is perceived when the retinal surface of the human visionsystem is illuminated with the group of optical wavelengths in theregion characterized by {λ_(B), Δζ_(B) }.

The operation of the SMCI camera system shown in FIG. 4 will bedescribed below with reference to the flow chart of FIG. 4B. Asindicated at Block Ain FIG. 4B, during a first recording period T1measured by recording controller, a first pair of left and rightperspective color images of a 3-D scene or object, I_(L) and I _(R), areformed through left and right image forming lenses 16A and 16B,respectively. As indicated at Block B in FIG. 4B, during the firstrecording period, the recording controller 21 provides a first set ofcontrol signals to the left optical image spectrum multiplexer 20A sothat this electro-optical element selectively multiplexes (e.g., passesor transmits ) a first group of spectral components SCG1 through theoptical image combiner 17 and onto the color image detector 18 tothereby form a first spectrally filtered image I_(L1) thereon. Duringthe first recording period, the recording controller also provides asecond set of control signals to the right optical image spectrummultiplexer 20B so that this electro-optical element selectivelytransmits a second group of spectral components SCG2 through the opticalimage combiner 17 and also onto the color image detector 18 to therebyform a second spectrally filtered image I_(R1) thereon. Together, thefirst and second groups of spectral components (i.e., spectrallyfiltered images I_(L1) and I_(R1))provide sufficientenergy to form afirst spectrally-multiplexed color image I_(SMCI) (1,k) of the 3-Dscenery on the color image detector 18. In response to this incidentenergy pattern, color image detector 18 produces a first digital dataset representative of the intensity and color of the pixels comprisingthe first spectrally-multiplexed color image I_(SMCI) (1,k). Asindicated at Block C in FIG. 4B, the recording controller 21 writesdigital pixel data representative of the first spectrally-multiplexedcolor image into the image buffer 19 operably associated with the colorimage detector 18. Then as indicated at Block D in FIG. 4B, during asecond recording period T2 measured by the recording controller, asecond pair of left and right perspective color images, I _(L) and I_(R) of the same 3-D scene or object are formed once again through leftand right image forming lenses 16A and 16B, respectively. As indicatedat Block E inFIG. 4C, during the second recording period, the recordingcontroller 21 provides the second set of control signals to the leftoptical image spectrum multiplexer 20A so that electro-optical element20A selectively transmits the second group of spectral components SCG2through the opticalimage combiner 17 and onto the color image detector18, to thereby form a third spectrally filtered image I _(L2). Alsoduring the second recording period, the recording controller 21 providesthe first set of control signals to the right optical image spectrummultiplexer 20B so that electro-optical element 20B selectivelytransmits the first group of spectral components SCG1 through theoptical image combiner 17 and onto the color image detector 18., tothereby form a fourth spectrally filteredimage I _(R2). Together, thefirst and second groups of spectral components (i.e., third and fourthspectrally filtered images I _(L2) and I _(R2)) form a secondspectrally-multiplexed color image I_(SMCI)(2,k) of the 3-D scene on thecolor image detector. In response to this incident energy pattern, thecolor image detector produces a second digital data set representativeof the intensity and color of the pixels comprising the secondspectrally-multiplexed color image I_(SMCI) (2,k).As indicated at BlockF in FIG. 4C, the recording controller 21 writes digital pixel datarepresentative of the second spectrally-multiplexed color image into theimage buffer 19 , operably associated with the color image detector. Asindicated at Block G, the first and second spectrally-multiplexed colorimages are then co-indexed in buffer memory by the recording controllerin order to produce a first spectrally-multiplexed color image pair{I_(SMCI) (1,k)I_(SMCI) (2,k)}. As indicated at Block H, theabove-described process is repeated cyclically at a rate equal to orgreater than the 30 image frames per second in order to produce asufficient number of spectrally-multiplexed color image pairs to supportstereoscopic viewing of the recorded 3-D scene during the stereoscopicdisplay process of the present invention.

The detailed structure of the optical image spectrum multiplexersemployed in the camera system of FIG. 4. will now be described. As shownin FIGS. 5A and 5B, the optical image spectrum multiplexer comprises anassembly ofoptically transparent electro-optical panels, namely: a firstplurality of polarizing filter panels 24 ,25 and 26, for passingspectral component bands Δλ₁, Δλ₂ and Δλ₃, respectively, while impartingeither a linear or circular polarization state P1 thereto; a secondplurality of polarizing filter panels 27, 28 and 29, for passingspectral component bands Δλ₄, Δλ₅ and Δλ₆, respectively, while impartingeither a linear or circular polarization state P2 thereto; avoltage-controlled half-wave phase retarding array panel 30 forimparting either a 0 or π radian phase shift to optical signals (e.g,light patterns) transmitted there through when controller 21providesvoltage levels V1 or V2, respectively, thereto; a broad optical bandpolarization panel 31 for imparting a linear or circularpolarizationstate P1 to optical signal (e.g. light pattern) transmittedtherethrough; and a picture-frame-like plastic housing 32 for supportingthe perimetrical edges of the above-described panels when they arelaminated together in the preferred spatial ordering shown, and also formounting a pair of electrical conductors 33A and 33B leading to thehalf-wave phase retarding panel. In general, the dimensions of theelectro-optical panel assembly will vary from embodiment to embodiment.However, typical length and width dimensions for the optical imagespectrum multiplexer might be 100 millimeters by 100 millimeters, withan overall thickness in the rangeof from about 1 to about 10millimeters. Typically, although not necessarily, the spectral componentbands of the first plurality of polarizing filter panels 24 through 26will be selected so as to correspond to a first set of visible colors,while the spectral component bands of the second plurality of polarizingfilter panels 27 to 29 will beselected so as to correspond to a secondset of visible colors. However, aswill be discussed in greater detailhereinafter, spectral component band selection and design should be madewith consideration to the amount of power present in the spectral bandsof the perspective images being recorded in order to achieve minimal"cross-viewing" between the left and right visual fields of viewersduring the stereoscopic display process of the present invention.Suitable methods for manufacturing each of the polarizing filter panels27 to 29 are disclosed in great detail in co-pending U.S. Pat. No.5,221,982 to Faris, which is incorporated herein by reference. Suitablemethods for manufacturing voltage-controlled half-wave retarding panel30 are disclosed in great detail in U.S. Pat. Nos. 4,719,507 to Bas and4,670,744 to Buzak, which are also incorporated herein by reference.Notably, construction and operation of the polarizingfilter panels 27 to29 depend on particular properties of chiral liquid crystals (CLC),commonly referred to as cholesteric liquid crystals. TheseCLC polarizingfilters operate according to the inherent "selective reflectionproperty" of cholesteric liquid crystals, and such, provide sharpspectral response characteristics which are highly desirable whenpracticing the present invention. Notably, however, it is also possibletouse conventional dichroic polarizing filters which operate on theinherent "adsorptive property" of dichroic materials in order topolarize spectral components of light. Details concerning the propertiesof liquid-phase cholesteric liquid crystals can be found in the paper byS. D. Jacobs , etal. at pages 1962-1978 of Journal of the OpticalSociety of America, B, Volume 5(9), September 1988. Details concerningthe properties of solid-state polymer-phase cholesteric liquid crystalscan be found in the paper by Robert Maurer at pages 110 et seq., ofSociety of Information Displays, SID 90 DIGEST, 1990.

In FIG. 5C, the spectrum for an exemplary optical image is schematicallyrepresented. Typically, an optical signal with such frequencycharacteristics is provided as an optical input signal to the inputsurface of each optical image spectrum multiplexer 20A and 20B. Asshown, this optical input signal comprises six bands Δλ₁, Δλ₂ Δλ₃, Δλ₄,Δλ₅, and Δλ₆, each centered about a central wavelength λ₁, λ₂, λ₃, λ₄,λ₅ and λ₆, respectively. When the recording controller 21 providescontrol voltage V=0 to half-wave phase retarding panel 30 of the opticalimage spectrum multiplexer, only the first group of spectral componentsSCG1 emerge from the output surface of the spectrum multiplexer, whilethe second spectral component group SCG2 is filtered out, as shown inFIG. 5D. In this state of operation, half-wave phase retarding panel 39does not convert the polarization stateof incoming optical signals. Whenthe recording controller 21 provides control voltage V=1 to thehalf-wave phase retarding panel of the spectrummultiplexer, only thesecond group of spectral components SCG2 emerge from the output surfaceof the spectrum multiplexer, while the first spectral component groupSCG1 is filtered out, as shown in FIG. 5E. In this state of operation,half-wave phase retarding panel 39 converts the polarizationstate ofincoming optical signals. Thus, when control voltages V_(L) =0 and V_(R)=1 are provided to the first and second optical imagespectrummultiplexers of camera system 15 during the first recordingperiod T1, and when the value of these control voltages are reversedduring second recording period T2, then a pair of spectrally multiplexedcolor images ofthe 3-D scene are produced for storage and subsequentdisplay.

The detailed structure of a particular embodiment of the optical imagespectrum multiplexer of FIG. 4 will now be described with reference toFIGS. 5B and 5F. As shown , each optical image spectrum multiplexer20A', 20B' comprises an assembly of optically transparentelectro-optical panels, namely: a polarizing filter panel 36 for passingspectral component band associated with the color green, while impartingeither a linear or circular polarization state P1 thereto; a pair ofpolarizing filter panels 37 and 38, for passing spectral component bandsassociated with the colors red and blue, respectively, while impartingeither a linear or circular polarization state P2 thereto ; avoltage-controlled half-wave (i.e. π radians) phase retarding arraypanel 39 for impartingeither a 0 or π radian phase shift to the opticalimage (e.g. optical signal) transmitted therethrough when recordingcontroller 21 provides voltage levels V1 or V2, respectively thereto; abroad band optical polarization panel 40 for imparting a linear orcircular polarization state P1 to light transmitted therethrough; andpicture-frame-like plastichousing 32 for supporting the perimetricaledges of the above panels when they are laminated together in thespatial ordering shown. As described above, frame-like housingfacilitates the mounting of electrical conductors 33A and 33B leading tohalf-wave phase retarding panel 39. In general, the dimensions ofelectro-optical panel assembly 35 will vary from embodiment toembodiment. However, typical length and width dimensions for the opticalimage spectrum multiplexer might be 100 millimeters by 100 millimeters,with an overall thickness in the range of from about 1 to about 10millimeters. Suitable methods for manufacturing each of the polarizingfilter panels 37 and 38 are disclosed in great detail in copending U.S.Pat. No. 5,221,982 to Faris, which is incorporated herein by reference.Suitable methods for manufacturing voltage-controlled half-waveretarding panel 39 are disclosed in great detail in U.S. Pat. Nos.4,719,507 to Bas and 4,670,744 to Buzak, which are also incorporatedherein by reference.

As illustrated in FIG. 5G, the spectrum for a typical color opticalimage provided input to the input side of optical image spectrummultiplexer 20A' and 20B', comprises three bands each centered about acentral wavelength. When the recording controller 21 provides controlvoltage V=0 to the half-wave phase retarding array panel of the spectrummultiplexer, only the first group of spectral components SCG1 associatedwith the colorgreen emerge from the output surface of the spectrummultiplexer, while thesecond spectral component group SCG2 associatedwith colors red and blue (i.e. magenta) is filtered out, as shown inFIG. 5H. When the recording controller 21 provides control voltage V=1to the half-wave phase retarding array panel of the spectrummultiplexer, only the second group of spectral components SCG2associated with the color magenta (i.e. red and blue) emerge from theoutput surface of the spectrum multiplexer, while the first spectralcomponent group SCG1 associated with the color green is filtered out, asshown in FIG. 51. By providing control voltages V=0 and V=1 to first andsecond optical image spectrum multiplexers 20A' and 20B' in the camerasystem of FIG. 4 during the first recording period T1, and thenreversing these control voltages during second recording period T2, apair of spectrally multiplexed color images of the 3-D scene areproduced for subsequent storage and display.

A solid-state camera system employing the optical image spectrummultiplexers of the present invention is shown in FIGS. 6A and 6B. Asshown, camera system 42 comprises a number of subcomponents, namely:firstand second image forming lenses 43A and 43B for forming left andright perspective color images, respectively, of a 3-D scene along firstand second optical axis's; first and second optical image spectrummultiplexers 20A' and 20B' disposed along the first and second opticalaxis's, respectively; an optical image combining element 44; a thirdimageforming lens 45; a CCD color image detecting array 46 operablyassociated with scanning electronics and an image frame buffer 47; andan image recording controller 48. As shown, optical image combiningelement 44 comprises first and second mirrors 49A and 49B disposed at 45degrees withrespect to the first and second optical axis's 50A and 50B,and third and fourth mirrors 51A and 51B, respectively, disposedparallel to the first and second mirrors respectively, so that the twicereflected optical images are optically coaxially combined and focused ina spatially coherent manner through the third image forming lens, toform a spectrally-multiplexed color image on the surface of the CCDimage detecting array. The image recording controller 48 generatescontrol signals to optical-image spectrum multiplexers 20A' and 20B',and CCD color image detecting array as described above. All of the abovedescribedcomponents are stationarily mounted with respect to an opticalbench 52, which is completely contained within a compact housing 53 ofrugged construction. The housing is provided with connector jacks inorder to supply electrical power to the camera system, whiletransmitting digitizedvideo output signals to a color video imagestorage device, such as a VCR recorder or video frame grabber, ordirectly or indirectly to a stereoscopic image display system of thepresent invention. The table shown in FIG. 6C sets forth the variouscontrol voltage signals which are provided to the optical image spectrummultiplexers of the camera system during six consecutive image recordingperiods Notably, two consecutive recording periods are required togenerate and record three pairs of spectrally multiplexed color imagesusing the camera system shown in FIGS.6A and 6B.

Referring to FIGS. 7A to 7E, solid-state camera system 55 not requiringtheoptical image spectrum multiplexers of FIG. 5F will be described. Thecamera system of this alternative embodiment of the present inventioncomprises a number of subcomponents, namely: first and second imageforming lenses 56A and 56B for forming left and right perspective colorimages of a 3-D scene, I _(L) and I_(R), respectively, along firstandsecond optical axis; first and second CCD color image detectingalways 57A and 57B, disposed along the first and second optical axis,respectively, for producing frames of digital color video datarepresentative of left and right perspective images formed throughlenses 56A and 56B; first and second color image frame buffers 58A and58B for buffering single frames of digital color video data producedfrom the first and second CCD image detecting arrays, respectively; apair of image frame buffer queues 59A and 59B, for buffering multipleframes of digital color video data sequentially produced from the firstand second CCD image detecting arrays57A and 57B, respectively; an imagerecording controller 60 for controllingthe transfer of frames of digitalvideo data from the first and second CCD image detecting arrays to thefirst and second image frame buffers, and from the first and secondimage frame buffers to the first and second image frame buffer queues,respectively; a digital data processor 61 for simultaneously retrievingframes of digital image data from the first and second image framebuffer queues (representative of pairs of left and right perspectiveimages), and processing the same in accordance with the algorithm setforth in the flow chart of FIGS. 7B through 7E, so as to produce framesof digital data representative of pairs of spectrally multiplexed colorimages {I_(SMCI) (1,k),I_(SMCI) (2,k)}; a high speeddata storage memory(e.g., VRAM) 62 for setting up a plurality of image frame buffers neededduring the data process; a mass-type data storage device 63 for storinga large number of frames of digital video data representative of pairsof spectrally multiplexed color images {I_(SMCI)(1,k), I_(SMCI) (2,k)};and a serial data transmission subsystem 64 having means for convertingframes of such digital image data into serial streams of digital videooutput signals, and means for transmitting the same along a serial datacommunication channel. All of the above describedcomponents arestationarily mounted with respect to an optical bench 65, which iscompletely contained within a compact housing 66 of rugged construction.The housing is provided with connector jacks 66 in order to supplyelectrical power to the electronic, electro-optical and electricalcomponents of the camera system, while transmitting the serial videodata output signals to either a color video image storage device, suchas a VCRrecorder or video frame grabber, or directly or indirectly to astereoscopic image display system of the present invention.

In general, each perspective color image formed on the CCD imagedetecting array 58A and 58B comprises a matrix of pixels ,each having acolor value representative of the spectral content of the image at thepixel's location in the image. During each recording cycle, CCD imagedetecting arrays 57A and 57B generate, for each perspective imagecaptured, a frame of digital data representative of the intensity andcolor of each pixel inthe detected perspective color images. Typically,the color value of each pixel contains a magnitude for each of thespectral components comprising the system of color representation (e.g,red, green, blue) being used. In the camera system shown in FIG. 7A,frames of digital video data representative of each pair of perspectiveimages captured by CCD image detecting arrays 57A and 57B areimmediately buffered in first and second image buffers 58A and 58B.These frames of digital video data are subsequently accessed by imagerecording controller 60 and buffered in first and second image framebuffer queues 59A and 59B. Thereafter, framesof digital video data areprocessed by image data processor 61 in accordance with thespectral-multiplexing algorithm illustrated in FIGS. 7B through 7E

As illustrated in FIGS. 7B through 7E, the spectral-multiplexingalgorithm comprises six data processing stages which cooperativelyproduce pairs of spectrally-multiplexed color images {I_(SMCI)(1,k),I_(SMCI) (2,k)} that can be used to stereoscopically display 3-Dscenery recorded by the camera system of FIG. 7A. However, in order toachieve computational efficiency, the first, second, fourth and fifthdata processing stages canbe performed in parallel as shown.

As illustrated at Block A in FIG. 7B, image data processor 61 performsthe first step in the first stage of the spectral-multiplexing algorithmby accessing from the first image frame buffer queue 59A, a frame ofdigital data representative of a left perspective color image I_(L) ofrecorded 3-D scenery, where each pixel therein is designated as:P(x_(i),y_(j))=({x_(i),y_(j) },{r_(i),j }, {g_(i),j },{b_(i),j }), andi=0,1, . . . N-1 and j=0,1, . . . , M-1. At Block B, for each pixelP_(L) (X_(i),y_(j)) in the left color 0perspective image I_(L), theprocessor selects the color value (i.e. color codes) associated with thefirst predefined spectral component group SCG1 (i.e. {r}, {b}). Then atBlock C the processor writes the selected pixel color value to thecorresponding pixel location in a first image buffer set up in datastorage memory 62. When at Block D the processor determines that thelast pixel in the left perspective image has been processed (i.e. i=N-1and j=M-1), the image processing operations set forth at Blocks Ethrough H are carried out. If desired or required, the image processingoperations set forth at Blocks A' through D' can be carried out inparallel with the corresponding operations at Blocks A through D using asecond image buffer set up in data storage memory 62. For purposes ofcompletion, these pixel-data processing operations will be described indetail below.

As illustrated at Block A' in FIG. 7A, the first step in the secondstage of the spectral-multiplexing algorithm involves accessing from thesecond image frame buffer queue 59B, a frame of digital datarepresentative of the right perspective color image IR where each pixeltherein is designated as :P(x_(i),y_(j))=({x_(i),y_(j) }, {r_(i),j},{g_(i),j }, {b_(i),j }), and i=0,1, . . . N-1 and j=0,1, . . ., M-1.AtBlock B', for each pixel P_(R) (x_(i),y_(j)) in the right colorperspective image I_(R), the processor selects the color value (i.e.color code) associated with the second predefined spectral componentgroupSCG2 (i.e. {g}). Then at Block C' the processor writes the selectedpixel color value to the corresponding pixel location in a second imagebuffer set up in data storage memory 62. When the processor determinesat Block D' that the last pixel in the right perspective image has beenprocessed (i.e. i=N-1 and j=M-1), the processor proceeds to Block E inFIG. 7B.

At Block E in FIG. 7C, the processor processes the spectrally filteredimages residing in the first and second image buffers so as to produce afirst spectrally-multiplexed color image I_(SMCI). As indicated atBlockE, for each pair of spatially corresponding pixels in thespectrally filtered images buffered in the first and second imagebuffers, the processor adds together corresponding color values {r_(x),y}, {g_(x),k }, {b_(x),y } in order to yield the (i,j)-thspectrally-multiplexed pixel P_(SMCI) (x_(i), y_(j)) in the firstspectrally-multiplexed color image I_(SMCI) (1,k). in the k-th stereopair thereof. Then at Block F, the processor writes thespectrally-multiplexed pixel P_(SMCI) (x_(i), y_(j)) into its spatiallycorresponding pixel location in a third image buffer set up in datastorage memory 62. As indicated at Block G, these pixel-data processingoperations are performed for each set of spatially corresponding pixelsresiding in the first and second image buffers, untilthe entire firstspectrally-multiplexed color image L_(SMCI) (1,k). is generated (i.e.,i=N-1 and j=M-1). Then at Block H, the first spectrally-multiplexedcolor image I_(SMCI) (1,k). is stored in mass-type data storage memory63. Thereafter, the processor performs operations necessary to producethe second spectrally-multiplexed color image I_(SMCI) (2,k) associatedwith the k-th stereo image pair thereof.The details of these pixel-dataprocessing operation will be described below.

As illustrated at Block I in FIG. 7D, the first step in the fourth stageofthe spectral-multiplexing algorithm involves accessing once again fromfirst image buffer queue 59A, the same frame of digital datarepresentative of the left perspective color image I_(L) where eachpixel therein is designated as :P(x_(i), y_(j))=({x_(i), y_(j) },{r_(i),j }, {g_(i),j }, {b_(i),j }), and i=0,1, . . . N-1 and j=0,1,. .. , M-1. At Block J, for each pixel P_(L) (X_(i),y_(i)) in the leftcolor perspective image I_(L), the processor selects the color value(i.e. color code) associated with the second predefined spectralcomponent group SCG2 (i.e. {g}). Then at Block K the processor writesthe selected pixel color value to the corresponding pixel location in afourthimage buffer set up in data storage memory. When the processordetermines at Block L that the last pixel in the left perspective imagehas been processed (i.e. i=N-1 and j=M-1),the processor proceeds toBlock M. While the image processing operations set forth at Blocks Mthrough P are being carried out, preferably the corresponding pixel dataprocessing operationsset forth at Blocks I' through L' are carried outin parallel. For purposesof completion, these pixel-data processingoperations will be described below.

As illustrated at Block I' in FIG. 7D, the first step in the fifth stageofthe spectral-multiplexing algorithm involves accessing once again fromsecond image frame buffer queue 59B, the same frame of digital datarepresentative of the left perspective color image I_(R) where eachpixel therein is designated as :P(x_(i), y_(j))=({x_(i), y_(j) },{r_(i),j }, {g_(i),j }, {b_(i),j }), and i=0,1, . . . N-1 and j=0,1,. .. , M-1. At Block L', for each pixel P_(R) (x_(i), y_(j)) in the rightcolor perspective image I _(R), the processor selects the color value(i.e. color codes) associated with the first predefined spectralcomponent group SCG1 (i.e. {r}, {b}). Then at Block K' the processorwritethe selected pixel color value to the corresponding pixel locationin a fifth image buffer set up in a data storage memory 62. When theprocessor determines at Block L that the last pixel in the rightperspective image has been processed (i.e. i=N-1 and j=M-1), theprocessor proceeds to BlockM in FIG. 7E.

At Block M in FIG. 7E, the processor processes the spectrally filteredimages residing in the fourth and fifth image buffers so as to producethesecond spectrally-multiplexed color image I_(SMCI) (2,k). Asindicated atBlock M', for each pair of spatially corresponding pixels inthe spectrallyfiltered images buffered in the fourth and fifth imagebuffers, the processor adds together the corresponding color values{r_(x), y }, {g_(x), k }, {b_(x),y } in order to yield the (i,j)-thspectrally-multiplexed pixel P_(SMCI) (X_(i), y_(j)) in the secondspectrally-multiplexed color image I_(SMCI) (2,k). in the k-th stereoimage pair thereof. Then at Block N the processor writes thespectrally-multiplexed pixel P_(SMCI) (x_(i), y_(j)) into its spatiallycorresponding pixel location in a sixth image buffer set up in datastorage memory 62. As indicated at Block 0, these pixel processingoperations are performed for each set of spatially corresponding pixelsresiding in the fourth and fifth image buffers until the entire secondspectrally-multiplexed color image I_(SMCI) (2,k). is generated. ThenatBlock P, the second spectrally-multiplexed color image I_(SMCI) (2,k).isstored in mass-type data storage memory 63 along with the firstspectrally-multiplexed color image L_(SMCI) (1,k). for future accessanddisplay. Together, the first and second spectrally-multiplexed colorimagescomprise a spectrally-multiplexed color image pair {I_(SMCI)(1,k), I_(SMCI) (2,k)}, containing sufficient visual information forstereoscopic viewing of the 3-D scenery recorded by the camera system ofFIG. 7A. The above-described image processing method can be repeatedupon left and right perspective color images of recorded 3-D scenery inorder to produce spectrally-multiplexed color image pairs at asufficiently highrate to support 3-D stereoscopic viewing . Noveltechniques for stereoscopically displaying pairs ofspectrally-multiplexed color images produced by the SMCI camera systemshereof, will be described hereinafter.Notably, while FIGS. 7A to 7Eteaches a digital camera and data processing technique, it is understoodthat analog signal processing circuitry can bereadily adapted for use inconstructing a camera system with such functionalities.

Referring to FIGS. 8A and 8B, a generalized method for displayingspectrally-multiplexed color images using electrically-active polarizingeyewear will now be described. As illustrated in FIGS. 8A and 8B,display system 68 comprises a number of components, namely: video randomaccess memory (VRAM) 69 for storing frames of digital video datarepresentative of spectrally-multiplexed color images of 3-D scenery; aflat liquid crystal display(LCD) panel 70 consisting of a matrix ofactively driven pixel elements; LCD driver circuitry 71 for driving thepixels of the LCD panel; an image display controller (e.g., programmedmicroprocessor) 72 for accessing frames of digital video data from VRAM69 and providing the same to LCD driver circuitry 71 so thatspectrally-multiplexed color images are visually displayed on LCD panel70 at a rate in excess of 30 frames per second; and lightweightspectacles 73 comprising a pair of electrically-active polarizing lenses74A and 74B mounted in a frame 75. The function of spectacle 73 is toimpart time dependent polarization states to particular spectralcomponent groups of light emitted from the LCD panel, during the imagedisplay process. As illustrated, each polarizing lens comprises anoptical process. As shown, each lens 75 comprises an image spectrumpolarizer 76 laminated directly onto a broad band optical polarizer 77.The broad band optical polarizer for the left lens 74A is characterizedby either a linear or circular polarization state P2, whereas the broadband optical polarizer for the right lens 74B is characterized by eithera linear or circular polarization state P1. Notably, display panel 70can be realized using alternative image display technology including,for example, CRT display devices, LCD flat panel display panels, plasmadisplay panels, electroluminescent display panels and the like.

As shown in FIG. 8A, the display controller displays a firstspectrally-multiplexed color image of a 3-D scene on the LCD panelduring a first display period. As illustrated in FIG. 8A, thisspectrally-multiplexed color image contains only the first spectralcomponent group SCG1 of the left perspective image and the secondspectralcomponent group SCG2 of the right perspective image. During thisdisplay period, display controller 72 provides a first control signalV_(L) to the left polarizing lens 74A, changing its spectraltransmission characteristics so that only the first spectral componentgroup SCG1 of the left perspective image can propagate from the displaysurface, throughthe transmission medium (e.g. air) 78, and be viewed bythe left eye of theviewer. At the same time, the display controller 72provides a second control signal V_(R) to the right polarizing lens 74Bchanging its spectral transmission characteristics so that only thesecond spectral component group SCG2 of the right perspective image canpropagate from thedisplay surface, through the transmission medium andbe viewed by the righteye of the viewer. Then as shown in FIG. 8B, thedisplay controller displays a second spectrally-multiplexed color imageof the same 3-D sceneon the LCD panel during a second display period. Asillustrated in FIG. 8B,this spectrally-multiplexed color image containsonly the second spectral component group SCG2 of the left perspectiveimage and the first spectral component group SCG1 of the rightperspective image. During this display period, the display controllerprovides the second control signal to the left polarizing lens 74Achanging its spectral transmission characteristics so that it allowsonly the second spectral component groupSCG2 of the left perspectiveimage can propagate from the display surface, through the transmissionmedium, and be viewed by the left eye of the viewer. At the same time,the display controller 72 provides the first control signal to the rightpolarizing lens 74A changing its spectral transmission characteristicsso that only the first spectral component group SCG1 of the rightperspective image can propagate from the display surface, through thetransmission medium, and be viewed by the right eye of the viewer. Asthis cyclical display process is repeated at least thirty times persecond, the spectral components of the left and right perspective imagesare effectively provided to the left and right eyes of the viewer,permitting full color stereoscopic viewing of the 3-D scene withoutimage-flicker.

The detailed structure of optical image spectrum polarizers 74A, 74B isschematically illustrated in FIGS. 9A and 9B. As shown, each opticalimagespectrum polarizer of the illustrative embodiment generallycomprises an assembly of optically transparent electro-optical panels,namely: a first plurality of passive polarizing filter panels 80, 81 and82, for passing spectral component bands Δλ₁, .sup.Δλ₂and Δλ₃,respectively, while imparting either a linear orcircular polarizationstate P1 thereto; a second plurality of passive polarizing filter panels83, 84 and 85, for passing spectral component bands Δλ₄, Δλ₅ and Δλ₆,respectively, while imparting either a linear or circular polarizationstate P2 thereto; a voltage-controlled half-wave phase retarding panel86 for imparting either a 0 or π radian phase shift to the optical image(e.g., optical signal) transmitted therethroughwhen display controller72 provides voltage levels V_(L) or V_(R) thereto; and frame-likeplastic housing 87 for supporting the perimetricaledges of the abovepanels when they are laminated together in the spatial ordering shown,and also for mounting a pair of electrical conductors 88A and 88Bleading to the half-wave phase retarding panel 86. In general,thedimensions of electro-optical panel assembly will vary fromembodiment to embodiment. However, typical length and width dimensionsfor the optical image spectrum polarizer will typically be 50millimeters by 50 millimeters. The thickness of the electro-opticalpanel assembly between optically transparent input and output surfaces89 and 90 will typically be in the range of from about 1 to about 10millimeters, although such dimensions may vary from embodiment toembodiment.

Typically, although not necessarily, the spectral component bands of thefirst plurality of polarizing filter array panels will be selected so asto correspond to a first set of visible colors, while the spectralcomponent bands of the second plurality of polarizing filter panels areselected so as to correspond to a second set of visible colors. However,in order to minimize "cross-viewing" between the left and right visualfields of viewers during the stereoscopic display process of the presentinvention, spectral component band selection and design will be bestmade with consideration to the amount of power present in the spectralbands ofperspective images utilized in producing thespectrally-multiplexed images.Suitable methods for manufacturing each ofthe polarizing filter panels 80 to 85 are disclosed in great detail inco-pending U.S. Pat. No. 5,221,982 to Faris. Suitable methods formanufacturing voltage-controlled half-wave retarding panel 86 aredisclosed in great detail in U.S. Pat. Nos. 4,719,507 to Bas and4,670,744 to Buzak. The construction and operation ofthe polarizingfilter array panels is based upon the selective reflective property ofcholesteric liquid crystals.

As illustrated in FIG. 9C, the spectrum of an exemplary optical imageprovided to the optically transparent input surface of each opticalimage spectrum polarizer comprises six bands Δλ₁, Δλ₂ Δλ₃, Δλ₄, Δλ₅, andΔλ₆, each centered about a central wavelength λ₁, λ₂, λ₃, λ₄, λ₅ λ₆.,respectively. Whenever display controller 72 provides control voltageV=0 to the half-wave phase retarding panel 86, the first group ofspectral components SCG1 emerge from the output surface of the spectrumpolarizer with polarization state P1, while the second spectralcomponent group SCG2 emerges with polarization state P2. Wheneverdisplay controller 72 provides control voltage V=1 to the half-wavephase retarding array panel of the spectrum polarizer, the second groupof spectral components SCG2 emerge from the output surface of thespectrum polarizer with polarization state P1, whilethe first spectralcomponent group SCG1 emerges with polarization state P2.Thus as shown inFIGS. 9D and 9E, when control voltages V_(L) =0 and V_(R) =0 areprovided to the first and second optical image spectrum polarizers 74Aand 74B in polarizing spectacles 73 during each first display period T1,and when the values of these control voltages are changed to `1` duringeach second display period T2, then only the spectral componentsassociated with the left perspective image(s) of the 3-D scene aretransmitted to the left eye of the viewer through broad bandpolarizer(P2) 77, while only the spectral components associated with the rightperspective image(s) thereof are transmitted to the right eye oftheviewer through broad band polarizer (P1) 77. During each first andsecond consecutive display periods, fusion of these spectral componentsoccurs within the vision system of the viewer, thereby providing theviewer with full color and depth perception of the 3-D scene.

The detailed structure of a particular embodiment of the optical imagespectrum polarizers 74A, 74B is schematically illustrated in FIGS. 9Fand 9B. As shown, optical image spectrum polarizer 74A', 74B' comprisesan assembly of optically transparent electro-optical panels, namely: apassive polarizing filter panel 92 for passing the spectral componentband Δλ_(G) associated with the color green, while imparting either alinear or circular polarization state P1 thereto; a pair of passivepolarizing filter panels 93 and 94, for passing spectral componentbandsassociated with the colors red and blue, respectively, while impartingeither a linear or circular polarization state P2 thereto; avoltage-controlled half-wave phase retarding panel 95 for impartingeithera 0 or π radian phase shift to optical images transmittedtherethrough when display controller 72 provides voltage levels V=0 andV=1 thereto, respectively; and the frame-like plastic housing 87 forsupporting the perimetrical edges of the above panels when they arelaminated together inthe spatial ordering shown, and also for mounting apair of electrical conductors 88A and 88B leading to half-wave phaseretarding panel 95. In general, the dimensions of this electro-opticalpanel assembly will vary from embodiment to embodiment. However, in apreferred embodiment typical length and width dimensions for eachoptical image spectrum polarizer willbe 50 millimeters by 50millimeters, with an overall thickness in the rangeof from about 1 toabout 10 millimeters. Suitable methods for manufacturingeach of thepolarizing filter panels 92 to 94 are disclosed in great detailincopending U.S. Pat. No. 5,221,982 to Faris. Suitable methods formanufacturing voltage-controlled half-wave retarding panel 95 aredisclosed in great detail in U.S. Pat. Nos. 4,719,507 to Bas and4,670,744to Buzak.

As illustrated in FIG. 9G, the spectrum for a typical color opticalimage provided input to the optically transparent input surface of eachoptical image spectrum polarizer 74A' and 74B', comprises three bandsΔλ_(R), Δλ_(G) and Δλ_(B), each centered about a central wavelengthλ_(R), λ_(G) and λ_(B)., respectively. Whenever the display controller72 provides control voltage V=0 to the half-wave phase retarding arraypanel 95, the first group of spectral components SCG1 associated withthe colorsblue and red (i.e. magenta) emerge from the output surface ofthe spectrum polarizer with polarization state P1, while the secondgroup of spectral components SCG2 associated with color green emergewith polarization stateP2. In this state of operation, half-wave phaseretarding panel 95 does notconvert the polarization state of spectrallypolarized optical signals. Whenever the display controller 72 providescontrol voltage V=1 to the half-wave phase retarding panel 95, thesecond group of spectral components SCG2 associated with the color greenemerge from the output surface of the spectrum polarizer withpolarization state P2, while the first group of spectral components SCG1associated with the color magenta emerge with polarization state P1. Inthis state of operation, half-wave phase retarding panel 95 converts thepolarization state of incoming optical signals. Thus as shown in FIGS.9H and 91, when control voltages V_(L) =1 and V_(R) =1 are provided tofirst and second optical image spectrum polarizers 74A and 74B duringeach first display period T1, and then the values of these controlvoltages are changed to "1" during each second display period T2, thenonly the spectral components associated with the left perspective imageof the 3-D scene are transmitted to the left eye of the viewer throughbroad band optical polarizer (P2) , while only the spectral componentsassociated with the right perspective image thereof are transmitted tothe right eye of the viewer through broad band optical polarizer (P1).During each first and second consecutive display period, fusion of thesespectral components occurs within the vision system of the viewer,providing full color and depth perception of the 3-Dscene.

In FIG. 10A, an alternative LCD embodiment of the display system ofFIGS. 8A and 8B is shown. As illustrated, LCD system 97 comprises anumber of components, namely: one or more devices 98 for producingframes of digitalvideo data representative of spectrally-multiplexedimages of 3-D scenery; a flat liquid crystal display(LCD) panel 99consisting of a matrix of pixel elements; LCD driver circuitry 100 fordriving the pixels of the LCDpanel; an image display controller (e.g.,programmed microprocessor) 101 for receiving frames of digital videodata from one or more devices 98 andproviding the same to LCD drivercircuitry 100 so that spectrally-multiplexed color images are visuallydisplayed on LCD panel 99at a rate in excess of 30 frames per second; aninfrared transmitter 102 for receiving control signals from the displaycontroller and transmittingthese signals onto a modulated carrier in theinfrared region of the electromagnetic spectrum; an infrared receiver103 for receiving the transmitted carrier signals and demodulating thesame to recover the control signals from the display controller; andlightweight spectacles 75, constructed from a pair ofelectrically-active polarizing lenses 74A and 74B for imparting timedependent polarization states to particular spectral component groups oflight emitted from the LCD panel during the image display process sothat the 3-D scene can be stereoscopically viewedtherethrough in colorand with full depth perception. As illustrated, each polarizing lens74A, 74B comprises an optical image spectrum polarizer 76 which isdirectly laminated onto a broad band optical polarizer 77, andisresponsive to control signals V_(L) or V_(R) recovered from infraredreceiver 103. The broad band optical polarizer 77 for the left lens 74Aischaracterized by either a linear or circular polarization state P2,whereasthe broad band optical polarizer for the right lens 74B ischaracterized byeither a linear or circular polarization state P1.Polarizing lenses 74A, and 74B, infrared receiver103 along with itsantenna element 104 each mounted within plastic spectacle frame 75 shownin greater detail in FIG. 10C. The construction and operation of eachoptical image spectrum polarizer 74A and 74B is identical to thatdescribed in connection with the optical image spectrum polarizer shownin FIG. 9A. The table shown in FIG. 10B sets forth the spectralcomponents of display outputs, polarization states of spectralcomponents thereof, and various control voltage signals V_(L) and V_(R)provided to the optical image spectrumpolarizers of the display systemduring six consecutive image display periods.

In FIG. 11A, a projection type embodiment of the display system of FIGS.8Aand 8B is shown. As illustrated, projection display system 106comprises a number of components, namely: a device 107 in accordancewith the present invention for producing frames of digital video datarepresentative of spectrally-multiplexed color images of 3-D scenery; acolor LCLV-type image projector 108 consisting of an illumination source109, a liquid crystal light valve(LCLV) 110, image projection lens 111and supporting electronics known in the image display art ; an LCLVdriver circuit 112 for actively driving the pixel elements of LCLV 110;an image display controller (e.g., programmed microprocessor) 112 forreceiving frames of digital video data from one or more devices 107 andproviding the same to LCLV driver circuit so that spectrally-multiplexedcolor images are visually displayed from LCLV 110 onto a reflectivedisplay surface 114 at a rate in excess of 30 frames per second; aninfrared transmitter 115 for receiving control signals from the displaycontroller 113 and transmittingthese signals onto a modulated carrier inthe infrared region of the electromagnetic spectrum; an infraredreceiver 116 for receiving the transmitted carrier signals anddemodulating the same to recover the control signals; and lightweightspectacles 75. In this particular embodiment of the present invention,electrically-active polarizing lenses74A and 74B mounted withinspectacles 73 impart time dependent polarizationstates to particularspectral component groups of light emitted from the LCLV projectionpanel 110 during the image display process. As a result, 3-D sceneryrepresented within the spectrally-multiplexed images being cyclicallydisplayed can be stereoscopically viewed through spectacles 73 with fulldepth perception. The table shown in FIG. 11B sets forth the spectralcomponents of display outputs, polarization states of spectralcomponents thereof, and various control voltage signals VL and VRprovidedto the optical image spectrum polarizers of the projection typedisplay system during six consecutive image display periods.

Referring to FIGS. 12A and 12B, a generalized method and system fordisplaying spectrally-multiplexed color images usingelectrically-passive polarizing eyewear will now be described. As shown,display system 120 comprises a number of components, namely: VRAM 121for storing frames of digital video data representative ofspectrally-multiplexed color images of 3-D scenery; a flat LCD panel 122consisting of a matrix of actively driven pixel elements; an opticalimage spectrum polarizer 123 laminated directly onto flat LCD panel 121for imparting time dependent polarizationstates to particular spectralcomponent groups of light emitted from the LCD panel during the imagedisplay process; LCD driver circuitry 125 for driving the pixels of theLCD panel; an image display controller (e.g., programmed microprocessor)124 for accessing frames of digital video data from VRAM 121 andproviding the same to LCD driver circuitry 123 so thatspectrally-multiplexed color images are visually displayed on the LCDpanel at a rate in excess of 30 frames per second; and lightweightspectacles 126 having a lightweight plastic frame 127 within which apair of polarizing lenses 128 and 129 are mounted. Structurally andfunctionally, optical image spectrum polarizing panel 123 is identicalto the electro-optical device illustrated in FIGS. 9A through 9H anddescribed above, except that the length and width dimensions of opticalimage spectrum polarizing panel 123 will conform substantially to thelength and width dimensions of LCD panel 122. Also, each polarizing lenswithin spectacles 126 is realized as a broad band optical polarizer. Thebroad band optical polarizer for left lens 128 is characterized byeither a linear or circular polarization state P2, whereas the broadband opticalpolarizer for right lens 129 is characterized by either alinear or circular polarization state P1.

As shown in FIG. 12A, display controller 124 displays a firstspectrally-multiplexed color image of a 3-D scene on LCD panel 122during each first display period. As illustrated in FIG. 12A, thisspectrally-multiplexed color image contains only the first spectralcomponent group SCG1 of the left perspective image and the secondspectralcomponent group SCG2 of the right perspective image. During thisdisplay period, the display controller provides a first control signalV_(OISP1)to optical image spectrum polarizer 123, thereby adjusting itsspectral polarizing characteristics so that the first spectral componentgroup SCG1of the left perspective image is imparted with a linear orcircular polarization state P1 upon emerging from its opticallytransparent output surface, while the second spectral component groupSCG2 of the right perspective image is imparted with a linear orcircular polarization stateP2 upon emerging from its opticallytransparent output surface. As a resultof the spectral polarizingfunctions performed by the optical image spectrum polarizer during eachfirst display period, the left polarized lens 128 characterized bypolarization state P2 permits only the first spectral component groupSCG1 of the left perspective image to propagate from the displaysurface, through transmission medium (e.g., air) 200 and pass to theviewer's left eye, while the right polarized lens 129 characterized bypolarization state P1 permits only the second spectral component groupSCG2 of the right perspective image to propagate from the displaysurface, through the transmission medium, and to the viewer's right eye.

As shown in FIG. 12B, the display controller displays a secondspectrally-multiplexed color image of a 3-D scene on the LCD panelduring a second display period. As illustrated in FIG. 12B, thisspectrally-multiplexed color image contains only the second spectralcomponent group SCG2 of the left perspective image and the firstspectral component group SCG1 of the right perspective image. Duringthis display period, the display controller provides a second controlsignal V_(OISP2) to the optical image spectrum polarizer 123, therebyadjustingits spectral polarizing characteristics so that the secondspectral component group SCG2 of the left perspective image is impartedwith a linear or circular polarization state P2 upon emerging from itsoptically transparent output surface, while the first spectral componentgroup SCG1 of the right perspective image is imparted with a linear orcircular polarization state P1 upon emerging from its opticallytransparent output surface. As a result of the spectral polarizingfunctions performed by theoptical image spectrum polarizer during eachsecond display period, the left polarized lens 128 characterized bypolarization state P2 permits only the second spectral component groupSCG2 of the left perspective image to pass to the viewer's left eye,while the right polarized lens 129characterized by polarization state P1permits only the first spectral component group SCG1 of the rightperspective image to pass to the viewer's right eye. As this cyclicaldisplay process is repeated at least thirty times per second, thespectral components of the left and right perspective images areeffectively provided to the left and right eyes of the viewer,permitting full color and stereoscopic viewing of the 3-D scene. Thetable shown in FIG. 12C sets forth the spectral components of displayoutputs, polarization states of spectral components thereof, and thecontrol voltage signals V_(OISP) provided to the optical image spectrumpolarizer of LCD type display system 120 during six consecutive imagedisplay periods.

A projection type embodiment of the display system of FIGS. 12A and 12Bis shown in FIG. 13A. As illustrated, projection display system 130comprisesa number of components, namely: a device 131 in accordance withthe presentinvention for producing frames of digital video datarepresentative of spectrally-multiplexed color images of 3-D scenery; acolor LCLV-type image projector 131 consisting of an illumination source132, a liquid crystal light valve(LCLV) panel 133; an LCLV drivercircuitry 134 for actively driving the pixels of LCLV panel 133; anoptical image spectrum polarizer 135 as shown in FIGS. 9A through 9H; animage projection lens 136 and supporting electronics known in the imagedisplay art an image display controller (e.g., programmedmicroprocessor) 137 for receiving frames of digital video data fromdevice 131 and providing the same to color projector 131 so thatspectrally-multiplexed color images are visually displayed on apolarization preserving display surface 138 at a rate in excess of 30frames per second; and lightweight electrically-passive spectacles 126described above. Preferably, optical image spectrum polarizer 135 isdirectly laminated onto LCLV projection panel 135, and is responsive tocontrol signals V_(OISP) generated by display controller 137 in order toimpart time dependent polarization states to particular spectralcomponent groups of light emitted from the LCLV projection panel duringthe image display process. The table shown inFIG. 13B sets forth thespectral components of display outputs, polarization states of spectralcomponents thereof, and the control voltage signals V_(OISP) provided tooptical image spectrum polarizer 135 during six consecutive imagedisplay periods in the projection type display system of FIG. 13A

FIGS. 14A and 14B show a portable notebook type computer system 140capableof displaying spectrally-multiplexed color images usingelectrically-passive polarizing eyewear 126 described above. Asillustrated in FIGS. 14A and 14B, portable notebook computer system ofthepresent invention comprises a number of integrated system components,namely: one or more central processing units 141 (e.g. microprocessor);hard-disc data storage device 142 for storing an operating systemprogram,application programs, and optionally various image processingroutines of the present invention; random access data storage memory(e.g. VRAM) 143 for buffering frames of digital video datarepresentative of spectrally-multiplexed color images of 3-D scenery orobjects; a mass-typedata storage memory 144 for long term storage ofproduced pairs of spectrally-multiplexed color images; a keyboard orother text input device145; a pointing and selecting device (.e.g.track-ball) 146; and one or more video output devices 147, such asCD-ROM or a stereo-image producing computer φr camera as shown in FIGS.3,4 or 6A; a flat LCD panel 148 consisting of a matrix of activelydriven pixels; LCD panel driver circuitry 149 for driving the pixels ofthe LCD panel; an optical image spectrum polarizer 150 (similar topolarizer panel 123 shown in FIGS. 12A and 12B) directly laminated ontoflat LCD panel 148 for imparting time dependent polarization states toparticular spectral component groups of optical images emitted from theLCD panel during the image display process; an image display controller(e.g., programmed microprocessor) 151for accessing frames of digitalvideo data from VRAM 143 and providing the same to LCD driver circuitry149 so that spectrally-multiplexed color images are visually displayedon the LCD panel at a rate in excess of 30 frames per second; andelectrically-passive lightweight polarizing spectacles 126 of the typeshown in FIGS. 12A, 12B, and 13A. As illustrated, these systemcomponents are operably associated with the processor 141 by way of oneor more system buses 152 in a manner known in the art. In a preferredembodiment, Macintosh System 7 operating system software from AppleComputer, Inc. or Windows operating system software from MicrosoftCorporation can be employed in order to enable processor 141 to supportat least two input/output windows, pointing and selecting device 146,and multi-media input and output devices 147. The operation ofthedisplay system aboard notebook computer 140 is essentially the same asdescribed in connection with the generalized LCD type display systemshownin FIGS. 12A and 12B.

As schematically illustrated in FIG. 15, there may be instances duringthe production of spectrally-multiplexed color images when either theleft and/or right perspective images lack sufficient energy in one ormore spectral component groups (i.e. {r} and {b}, and/or {g}). In suchinstances, the transient energy imbalance in the producedspectrally-multiplexed image will result in there being a moment or so,during the stereoscopic display process, when only one of the viewer'seyes is stimulated (i) with sufficient light energy from the primaryspectral component groups (e.g. {r} and {b}, and {g}) of the 3-D image,and (ii) for a predetermined period of time that is functionally relatedto the retinal response time of the human eye. Consequently when thiscondition exists in pairs of spectrally-multiplexed composite images,thenit is possible that some viewers may be more susceptible than othersin perceiving what appears to be "image-flicker" during the stereoscopicviewing process. In order to eliminate the possibility of suchimage-flicker perception during the stereoscopic viewing process, thefollowing techniques have been developed.

In accordance with the present invention, flicker free stereoscopicimages can be produced independent of the spectral power distribution ofperspective images by using the method of spectral-multiplexingillustrated in FIGS. 16A to 17G. In general, this method can be carriedout using the computer system of FIG. 3, the camera system of FIG. 7A,or any other computer-based SMCI producing system of the presentinvention. As in the case of the spectral multiplexing methods shown inFIGS. 3A to 3E and 7B to 7E, each perspective color image producedwithin and processed by the SMCI computer system comprises a matrix ofpixels. Each pixel in the image matrix is designated as P(x_(i),y_(j))=({x_(i), y_(j) }, {r_(i),j }, {g_(i),j }, {b_(i),j }), and has acomposite color value representative of the spectral content of theimage at the pixel's location in the image, indicated by the coordinatepair (x, y). Intypical color video applications, the color value of eachpixel contains a magnitude for each of the spectral components, e.g.{g_(i),j }, {b_(i),j }, {r_(i),j }, constituting the system of colorrepresentation being used in the illustrative embodiment. In the SMCIcomputer system of the present invention, the left and right colorperspective images are stored in data storage memory (e.g. framebuffers) 8 and are then processed by processor 6 in accordance with thespectral-multiplexing algorithm schematically illustrated in FIGS. 17Ato 17G. As shown in these figures, the "flicker-free"spectral-multiplexing algorithm also comprises plural stages ofpixel-data processing which collectively produce pairs ofspectrally-multiplexed color images for display and flicker-freestereoscopically viewing of the 3-D imagery represented in thecomputer-based system. To achieve computational efficiency, several ofthese stages can be performed in parallel as shown.

As illustrated at Block A in FIG. 17A, processor 6 performs the firststep in the first stage of the spectral-multiplexing algorithm byaccessing from data storage memory 8, a frame of digital datarepresentative of the left perspective color image I_(L) where eachpixel therein is designated as :P(x_(i), y_(j))=({x_(i), y_(j) },{r_(i),j }, {g_(i),j }, {b_(i),j }), and i=0,1, . . . , N-1 and j=0,1, .. . , M-1. At Block B, for each pixel P_(L) (x_(i), y_(j)) in the leftcolor perspective image I_(L), the processor selects the color value(i.e. color code) associated with the first predefined spectralcomponent group SCG1 (i.e. {r}, {b}) and determines whether the selectedcolor codeshave sufficient magnitude values (i.e. exceed a predeterminedpower threshold). Notably, this predetermined power threshold can bereadily determined by empirical investigation of the human visionsystem. If at Block C the processor determines that the selected colorcodes of pixel P_(L) (x_(i), y_(j)) have sufficient magnitude values,then at BlockD the processor updates the first pixel-filler image buffershown in FIG. 16A by writing the selected color codes in the spatiallycorresponding pixel location in the first pixel-filler image buffer setup in data storage memory 8. Thereafter the processor proceeds to BlockF and writes the selected color code to the spatially correspondingpixel location in the first image buffer set up in data storage memory.

While the pixel-data processing operations set forth at Blocks A throughF are being carried out, the corresponding pixel-data processingoperations set forth at Blocks A' through F' are preferably carried outin parallel using a second image buffer set up in data storage memory.For purposes ofcompletion, these operations will be described below.

As illustrated at Block A' in FIG. 17A, the first step in the secondstage of the spectral-multiplexing algorithm involves accessing fromdata storage memory 8, a frame of digital data representative of theright perspective color image IR where each pixel therein is designatedas :P(x_(i), y_(j))=({x_(i), y_(j) }, {r_(i),j }, {g_(i),j }, {b_(i),j}), and i=0,1, . . . N-1 and j=0,1, . . . , M-1. At Block B', for eachpixel P_(R) (x_(i), y_(j)) in the right color perspective image IR ,theprocessor selects the color value (i.e. color code) associated with thesecond predefined spectral component group SCG2 (i.e. {g}) anddetermines whether the selected color code has a sufficient magnitudevalue. If at Block C' the processor determines that the selectedcolorvalue of pixel P_(R) (X_(i), y_(j)) from the right perspective imageI_(R) has a sufficient magnitude value, , then at Block D' the processorupdates the second pixel-filler image buffer shown in FIG. 16A bywriting the selected color code in the spatially corresponding pixellocation in the second pixel-filler image buffer. Thereafter theprocessorproceeds to Block F' and writes the selected color code to thespatially corresponding pixel location in the second image buffer set upin the datastorage memory.

As indicated at Blocks H and I, the processor determines whether theselected color value of pixel P_(L) (x_(i), y_(j)) from the leftperspective image I_(L) and the selected color value of pixel P_(R)(x_(i), y_(j)) from the right perspective image I _(R) both lack asufficient magnitude value. If so, then the output of AND operation(BlockH) will be a logical 1. When this condition is determined at BlockI, then the processor proceeds to Block J in FIG. 17C. At Block J theprocessor determines whether a predetermined number of SMCI productionperiods have lapsed since the output of the AND operation at Block H wasa logical "0".Notably, this operation checks to determine whether thespatially corresponding pixel values in the left and right perspectiveimages both lack sufficient energy in the primary color values, a pixelcondition incapable of producing image flicker. If the predeterminednumber of SMCI production periods have elapsed, then at Block L theprocessor erases (e.g. sets to zero value) the color code(s) in thespatially correspondingpixel locations in both the first and secondpixel-filler image buffers. Thereafter the processor proceeds to Block Kin FIG. 17C and writes the selected color code(s) of the first spectralcomponent group SCG-1 in the spatially corresponding pixel location inthe first image buffer, and writes the selected color code(s) of thesecond spectral component group SCG-2 in the spatially correspondingpixel location in the second image buffer. Otherwise, if thepredetermined number of SMCI production cycles have not elapsed, thenthe processor proceeds directly from Block J to Block K, as shown. FromBlock K, the processor proceeds to Blocks G and G'in FIG. 17B.

However, if at Block I its determined that the output of the ANDoperation (at Block H) is not a logical "1", then the processor proceedsfrom Block C to Block E during the first processing stage, and fromBlock C' to BlockE' during the second processing stage, as shown in FIG.17A. At Block E theprocessor writes into the spatially correspondingpixel location in the first image buffer, the color codes {r} and {b} ofthe present (i.e. most recently updated) filler pixel taken from thespatially corresponding pixel location in the first pixel-filler imagebuffer. Similarly, at BlockE' the processor writes into thecorresponding pixel location in the secondimage buffer, the color code{g} of the present filler pixel taken from thespatially correspondingpixel location in the second pixel-filler image buffer, as shown in FIG.16A. When the processor determines at Blocks G and G' that the lastpixel in the left and right perspective images have been processed (i.e.i=N-1 and j=M-1), then the processor proceeds to Blocks M and N in FIG.17B. Only when the output of the AND operation at Block M is a logical"1", then the processor proceeds to Block O. Until this condition issatisfied, the high level flow of the process remains atBlock N,awaiting for the first and second spectrally filtered images tobeproduced.

At Block O, the processor processes the spectrally filtered imagesresidingin the first and second image buffers in order to produce afirst spectrally-multiplexed color image I_(SMCI) (1, k). Specifically,for each pair of spatially corresponding pixels in the pair ofspectrally filtered images buffered in the first and second imagebuffers, the processor adds together the corresponding color values{r_(x),y }, {g_(x),k }, {b_(x),y }in order to yield the (i,j)-thspectrally-multiplexed pixel P_(SMCI) (x_(i), y_(j)) in the firstspectrally-multiplexed color image L_(SMCI) (1,k). in the k-th stereoimage pair thereof. Then at Block P, the processor writes thespectrally-multiplexed pixel P_(SMCI) (x_(i), y_(j)) into its spatiallycorresponding pixel location in a third image buffer set up in datastorage memory 8, as shown in FIG. 16A. As indicated at Block Q, thesepixel-data processing operations are performed for each set of spatiallycorresponding pixels residing in the first and second image buffers,until the entire first spectrally-multiplexed color image L_(SMCI) (1,k). is generated (i.e., i=N-1 and j=M-1). Then at Block R, the firstspectrally-multiplexed color image I_(SMCI) (1,k). is stored in datastorage memory 9. As indicated at Block R, the processor thereafterproceeds to Blocks S and S' in order to commence the fourth andfifthstages of pixel-data processing, which produce the secondspectrally-multiplexed color image I_(SMCI) (2,k) of the k-th stereoimage pair thereof. The details of these pixel data processingoperations will be described below.

As illustrated at Block S in FIG. 17D, the first step in the fourthstage of the spectral-multiplexing algorithm involves accessing onceagain from data storage memory 8, the frame of digital datarepresentative of the left perspective color image IL where each pixeltherein is designated as : P(x_(i), y_(j))=({x_(i), y_(j) }, {r_(i),j },{g_(i),j }, {b_(i),j }), and i=0,1, . . .N-1 and j=0,1, . . . , M-1. AtBlock T, foreach pixel P_(L) (x_(i), y_(j)) in the left colorperspective image I_(L), the processor selects the color value (i.e.color code) associated with the second predefined spectral componentgroup SCG2 (i.e., {g}) and determines whether the selected color codehas a sufficient magnitude value. If at Block U the processor determinesthat the selected color value of pixel P_(L) (x_(i), y_(j)) from theleft perspective image I_(L) has a sufficient magnitude value, then atBlock V the processor updates the first filler-pixel image buffer shownin FIG. 16B bywriting the selected pixel color value to its spatiallycorresponding pixellocation. Thereafter the processor proceeds to BlockX and writes the selected color value to the corresponding pixellocation in the fourth image buffer set up in the data storage memory.While the processor carries out the image processing operations setforth at Blocks S through X, it preferably carries out in parallelcorresponding operations at Blocks S' through X' using a fifth imagebuffer set up in data storage memory 8. For purposes of completion,these pixel-data processing operations will be described below.

As illustrated at Block S' in FIG. 17D, the first step in the fifthstage of the flicker-free spectral-multiplexing algorithm involvesaccessing once again from data storage memory 8, the frame of digitaldata representative of the right perspective color image I_(R) whereeach pixel therein is designated as :P(x_(i), y_(j))=({x_(i), y_(j) },{r_(i),j }, {g_(i),j }, {b_(i),j }), and i=0,1, . . .N-1 and j=0,1, . .. , M-1. At Block T', for each pixel P_(R) (x_(i), y_(j))) in the rightcolor perspective image I_(R) ,the processor selects the colorvalue(i.e. color codes) associated with the first predefined spectralcomponent group SCG1 (i.e. {r}, {b}) and determines whether the selectedcolor value has a sufficient magnitude value. If at Block U' theprocessordetermines that the selected color value of pixel P_(R) (x_(i),y_(j)) from the right perspective image I _(R) has a sufficientmagnitude value, then at Block V' the processor updates the fourthpixel-filler image buffer shown in FIG. 16B by writing the selectedcolor codes to the spatially corresponding pixel location in a fifthimage buffer set up in data storage memory 8. Thereafter the processorproceeds to Block X' and writes the selected color codes to thespatially corresponding pixel location in the fifth image buffer, asillustrated in FIG. 16B.

As indicated at Blocks Y and Z, the processor determines whether theselected color values of pixel P_(L) (X_(i), y_(j)) from the leftperspective image I_(L) and the selected color value of pixel P_(R)(x_(i), y_(j)) from the right perspective image I _(R) both lack asufficient magnitude value. If so, then the output of AND operation(BlockY) will be a logical "1", and the processor proceeds to Block Z.At Block AA the processor determines whether a predetermined number ofSMCI production periods have lapsed since the output of the ANDoperation at Block Y was a logical "0". Notably, this operation checksto determine whether the spatially corresponding pixel values in theleft and right perspective images both lack sufficient energy in theprimary color values, a pixel condition incapable of producing imageflicker. If the predetermined number of SMCI production periods haveelapsed, then at Block CC the processor erases (e.g. sets to zero value)the color codes inthe spatially corresponding pixel locations in boththe first and second pixel-filler image buffers. Thereafter theprocessor proceeds to Block BB and writes the selected color codes ofthe second spectral component groupSCG-2 in the spatially correspondingpixel location in the fourth image buffer, and writes the selected colorcode(s) of the first spectral component group SCG-1 in the spatiallycorresponding pixel location in thefifth image buffer. Otherwise, if thepredetermined number of SMCI production cycles have not elapsed, thenthe processor proceeds directly from Block AA to Block BB, as shown.From Block BB, the processor proceedsto Blocks Y and Y'.

If however, at Block J the output of AND operation (at Block I) is not alogical "1", then the processor proceeds from Block U to Block W duringthe first processing stage, and from Block U' to Block W' during thesecond processing stage, as shown in FIG. 17D. At Block W the processorwrites into the spatially corresponding pixel location in the firstimage buffer, the color codes {g} of the present (i.e. most recentlyupdated) filler pixel taken from the spatially corresponding pixellocation in the first pixel-filler image buffer. Similarly, at Block W'the processor writes into the corresponding pixel location in the secondimage buffer, the color codes {r} and {b} of the present filler pixeltaken from the spatially corresponding pixel location in the secondpixel-filler image buffer, as shown in FIG. 16B. When the processordetermines at Blocks Y and Y' that the last pixel in the left and rightperspective images have been processed (i.e. i=N-1 and j=M-1), then theprocessor proceeds to Blocks DD and EE in FIG. 17E. Only when the outputof the AND operation atBlock DD is a logical "1", then the processorproceeds to Block FF. Until this condition is satisfied, the processremains at Block EE, awaiting forthe third and fourth spectrallyfiltered images to be produced.

At Block FF in FIG. 17E, the processor processes the spectrally filteredimages residing in the fourth and fifth image buffers so as to producethesecond spectrally-multiplexed color image L_(SMCI) (2,k). Asindicated atBlock FF, for each pair of spatially corresponding pixels inthe pair of spectrally filtered images buffered in the fourth and fifthimage buffers,the processor adds together the corresponding color values{r_(x),y }, {g_(x),k }, {b_(x),y } in order to yield the (i,j)-thspectrally-multiplexed pixel P_(SMCI) (x_(i), y_(j)) in the secondspectrally-multiplexed color image I_(SMCI) (2,k). in the k-th stereoimage pair thereof. Then at Block GG, the processor writes thespectrally-multiplexed pixel P_(SMCI) (x_(i), y_(j)) into its spatiallycorresponding pixel location in a sixth image buffer set up in datastorage memory 9, as shown in FIG. 16B. As indicated at Block HH, thesepixel-data processing operations are performed for each set of spatiallycorresponding pixels residing in the fourth and fifth image buffers,until the entire second spectrally-multiplexed color image I_(SMCI)(2,k). is generated. Then at Block II, the second spectrally-multiplexedcolor image I_(SMCI) (2,k). is stored in data storage memory 9 alongwith the first spectrally-multiplexed color image L_(SMCI) (1,k). forfuture access and display. Together, the first and secondspectrally-multiplexed color images comprise a spectrally-multiplexedcolor image pair {I_(SMCI) (1,k)} containing original pixel color codesand possibly "filler" pixel color codes that permit stereoscopic viewingof the original 3-D scene without visual perception of image flicker.

The above-described pixel-data processing method can be repeated uponleft and right perspective color images of either real or synthetic 3-Dimageryin order to produce spectrally-multiplexed color image pairs at asufficiently high rate to support flicker-free 3-D stereoscopic displayand animation processes. Any of the above-described display techniquescanbe used for stereoscopically displaying pairs ofspectrally-multiplexed color images produced by thespectral-multiplexing process described above.

Alternative techniques may be employed for stereoscopically displaying3-D images without image flicker. An alternative approach will bedescribed below.

In accordance with this alternative method, the spectral powerdistributions of perspective color images are analyzed in real-timeprior to producing and displaying spectrally-multiplexed color imagestherefrom.Using information collected from real-time spectral powerdistribution analysis, particular wavelengths are assigned to thespectral component groups (e.g. SCG1 and SCG2) associated withperspective images to be spectrally multiplexed during the SMCIproduction processes described above. Sg "adaptive spectralmultiplexing" can be achieved using a modified version of the camerasystem shown in FIG. 6A. Preferably, the adaptive SMCI camera systemincludes two mechanism, namely: a means for performing spectral powerdistribution analysis on perspective images presented to the camerasystem; and also a means for adapting the spectraltransmissioncharacteristics of the left and right optical image spectrummultiplexers utilized therein, to a prespecified criteria. The means forperforming spectral power distribution analysis can be realized using abeam splitting optics, an color image detecting array, and an imageprocessor programmed to perform spectral power distribution analysis andproduce an appropriate set of control signals on a real-time basis. Suchcontrol signals carry information representative of the wavelengthcharacteristics comprising the spectral component groups SCG1 and SCG2in each spectrally-multiplexed color image. Thus as the spectral powerdistribution of incoming perspective images changes from a predeterminedcriteria, so too will the spectral component groups SCG1 and SCG2 andthe control signals produced from the means for adapting the spectraltransmission characteristics of the left and right optical imagespectrum multiplexers. In a preferred embodiment, the means for adaptingthe spectral transmission characteristics of the left and right opticalimage spectrum multiplexers can be realized using optical image spectrummultiplexers having spectral transmission characteristics that can beselectively changed from recording period to recording period, inresponseto different control signals produced by the means forperforming spectral power distribution analysis. In a preferredembodiment, the prespecified criteria satisfied by the adaptive camerasystem would be to spectrally multiplex the perspective color images sothat the spectral power contained in each pair of left and rightperspective color images is substantially equally distributed betweenthe pair of spectrally-multiplexed images produced therefrom.

When using the above described adaptive camera system or a like devicefor producing spectrally-multiplexed color images, it will be necessaryto employ an adaptive display system in order to avoid the possibilityof flicker perception during the display process. This is particularlyimportant in instances where the left and right perspective images (usedto produce the displayed spectrally-multiplexed images) have severelyunbalanced spectral power distributions, as previously illustrated inFIG.15. An adaptive display system in accordance with the presentinvention would employ one or two "adaptive" optical image spectrumpolarizers, eachhaving spectral polarizing characteristics particularlyadapted to change in response to the control signals produced by theimage processor programmed to perform spectral power distributionanalysis during the spectral-multiplexed color image production process.With this adaptive display system, the wavelengths associated with thespectral component groups SCG1 and SCG2 defined during the SMCIproduction process, will be polarized during the image display processso that only the spectral components associated with the leftperspective image propagate through the transmission medium (e.g. air)to the viewer's left eye, while only the spectral components associatedwith the right perspective image propagate through the transmissionmedium to the viewer's right eye.

It is understood that the systems and components of the presentinvention will find numerous applications in diverse fields of humanendeavor including, for example, business, education, scientificresearch, entertainment and defense. Among these various fields, onesuch application is Stereo TeleVision (STV) entertainment andeducational services, in which the SMCI producing computer, camera orlike devices described above is used to supply analog or digital SMCIsignals to the central transmitting system 154 (e.g. station) of atelevision signal transmission and distribution system 155,schematically illustrated in FIG. 18. In general, the centraltransmitting system includes one or more television carrier signalgenerators and modulators, which can be used to modulated a televisioncarrier signal by a SMCI video signal, which functions as a modulationsignal. In turn, the central transmitting station can transmit themodulated television carrier signal over one or more channels 156 in thetelevision signal transmission and distribution system, to one or moreremote television signal receiving devices 157A, 157B. In general, eachsuch channel 156 can be realized as coaxial cable, fiber optical cableand/or the free-space medium, and transmission of suchmodulatedtelevision carrier signals may include the use of microwave or opticaltransmitters, receivers and/or transceivers, and frequency conversiondevices well known in the telecommunication art. At each such receivingdevice, the modulated television carrier signal can be redistributed toone or more SMCI display systems of the present invention3, whichincludes a SMCI display system of the present invention, such as 68, 97,106, 120, 130 and 140 described above. At each such SMCI display system,the modulated television carrier signal is demodulated and the recoveredSMCI signals (including the control signals VOISP) are used to displaythe spectrally-multiplexed color images as hereinbefore described.Asdiscussed above, such images will be displayed at a rate in excess of30video frames per second in order to provide flicker-free stereoscopicviewing of 3-D color images.

In FIG. 19, stereoscopic display system 120 described above is shownoperably connected to a remote receiving device 157A (e.g. a cabletelevision signal converter) present in television signal transmissionanddistribution system 155. As shown, electrically-active spectralpolarization panel 76 (123) is releasably mounted to the CRT displaysurface 161 of a conventional color television set 162, using a set offour suction cup type attachment devices 163A, 163B, 163C and 163D whichare fixedly connected to the corners of the plastic frame 87 of thespectral polarization panel 76, detailed in FIG. 9B. The spectralpolarization panel is mounted to the CRT display surface by simplypressing the frame against the CRT surface. The spectral polarizationpanel can be made in a variety of sizes in order to accommodate thevarious size image display surfaces of commercially available televisionsets.

In order to interconnect the spectral polarization panel to a remotereceiving device 157A (e.g. a cable television converter), a controlsignal regeneration device 165 is installed in-line between the TVsignal input connector 166 on the television set and the signal outputconnector 167 on the cable television signal converter, as shown. Withinthe compacthousing of the control signal re-generation device iselectronic circuitry which processes the analog SMCI television signalprovided to its input connector 171 in order to re-generate controlsignals V_(OISP) for inputto control terminals 88A and 88B of thespectral polarization panel, as described above in connection withstereoscopic display system 120. Preferably, the control signalre-generation device is powered by a long-life battery contained withinthe compact housing of the device.

As shown in FIG. 19, the control signal re-generation device can beinterconnected the television set and the cable television signalconverter by connecting a first section of coaxial cable 168 betweenconnector 166 and the output signal connector 169 on the control signalre-generation device, and then connecting a second coaxial cable section170 between the input connector 171 of the control signal re-generationdevice and the output connector of the cable television signalconverter. The control signal re-generation device 165 has an controlsignal output connector 172 which is operably connected to inputconductors 88A and 88B of the spectral polarization panel using asection of flexible shielded cable 173, as shown.

During the operation of the stereoscopic display system, the controlsignalre-generation device 165 analyzes the received SMCI televisionsignal provided to its input connector terminals, and generatestherefrom controlsignals V1, V2 described above. In turn, these controlsignals are providedto the spectral polarization panel 76 in order tocontrol the operation of tthereof while spectrally-multiplexed imagesare visually presented upon the CRT display surface of the televisionset. During this image display process, the the displayedspectrally-multiplexed images are viewed through passive polarizationspectacles 126 so that the 3-D imagery carried by the received SMCItelevision signal is viewed with full depth perception.

It is readily apparant that the above-described stereo televisiondisplay system has a number of advantages from a practical stand point.Foremost, the technique and system is completely compatible with NTSCStandards; it can be used in connection with non-planar display surfacesprovided by CRTdevices; it can be practiced in a manner substantiallyfree from image flicker; and it can be used with any conventionaltelevision set by simplymounting a spectral polarization panel to theCRT display surface thereof and inserting control signal re-generationdevice between a the televisionset and a section of incoming televisionsignal cable. Such accessories aresimple and inexpensive to manufactureand distribute to television viewers who desire to stereoscopically viewSTV™ programs in the comfort of their own home.

Having described the above illustrative embodiments of the presentinvention, several modifications readily come to mind.

In particular, digital equipment has been used in the illustrativeembodiments in order to support the processes of the present invention.Itis understood, however, that analog as well as hybrid analog anddigital equipment well known in the art can be readily adapted to carryout such processes in accordance with the teachings of the presentinvention disclosed herein.

While active-pixel type flat panel image display devices have beendisclosed in the illustrative embodiments, it is understood that suchimage display devices can include cathode ray tube(CRT) display devices,plasma display panels, passive back-lighted flat display panels,electro-luminescent display panels and the like without departing fromtheprinciples of the present invention.

The various embodiments of the present invention will be useful in manydiverse stereoscopic imaging applications. However it is also understoodthat various modifications to the illustrative embodiments of thepresent invention will readily occur to persons with ordinary skill inthe art. All such modifications and variations are deemed to be withinthe scope and spirit of the present invention as defined by the Claimsto Invention appended hereto.

What is claimed is:
 1. A system for visually presenting a pair ofspectrally-multiplexed images of a three-dimensional scene for use instereoscopic viewing thereof by a viewer having left and right eyes,said system comprising:image display means for sequentially displaying afirst spectrally-multiplexed image during a first display period and asecond spectrally-multiplexed image during a second display period, saidfirst spectrally-multiplexed image having a first group of spectralcomponents obtained from a first perspective image of saidthree-dimensional scene and a second group of spectral componentsobtained from a second perspective image of said three-dimensionalscene, and said second spectrally-multiplexed image having a secondgroup of spectral components obtained from said first perspective imageof said three-dimensional scene and a first group of spectral componentsobtained from said second perspective image; and electro-optical imageprocessing apparatus, disposed between said image display means and theleft and right eyes of the viewer, for alternatively processing saidfirst and second spectrally-multiplexed images as said first and secondspectrally-multiplexed images are visually presented to the left andright eyes of the viewer by said image presentation means, saidelectro-optical image processing means being operable during said firstdisplay period for processing said first spectrally-multiplexed image soas to selectively transmit only the first group of spectral componentsof said first perspective image to the left eye of the viewer and onlythe second group of spectral components of said second perspective imageto the right eye of the viewer during said first display period, andsaid electro-optical image processing apparatus being operable duringsaid second display period for optically processing said secondspectrally-multiplexed image so as to selectively transmit only thesecond group of spectral components of said first perspective image tothe left eye of the viewer and only the first group of spectralcomponents of said second perspective image to the right eye of theviewer during said second display period, whereby the first and secondgroups of spectral components of said first perspective image aretransmitted from said image display means to the left eye of the viewerover said first and second display periods, and the first and secondgroups of spectral components of said second perspective image aretransmitted from said image display means to the right eye of the viewerover said first and second display periods so that saidthree-dimensional scene can be stereoscopically viewed by the left andright eyes of the viewer.
 2. The system of claim 1, wherein said imagedisplay means comprises an image display panel, and wherein saidelectro-optical image processing apparatus comprises eyewear having afirst electro-optical elements positionable in front of the left eye ofthe viewer and a second electro-optical lens positionable in front ofthe right eye of the viewer.
 3. The system of claim 2, wherein saidfirst electro-optical element comprisesfirst optically transparent inputsurface through which the first and second groups of spectral componentscan enter said first electro-optical element, first opticallytransparent output surface through which the first and second groups ofspectral components can exit said first electro-optical element, andfirst spectral-component transmission means, disposed between the firstoptically transparent input and output surfaces of said firstelectro-optical element, for transmitting the first group of spectralcomponents of said first perspective image to the left eye of the viewerduring said first display period and transmitting the second group ofspectral components of said first perspective image to the left eye ofthe viewer during said second display period, while substantiallyblocking the transmission of the second and first spectral components ofsaid second perspective image during the first and second displayperiods, respectively, and wherein said second electro-optical elementcomprisessecond optically transparent input surface through which thefirst and second groups of spectral components can enter said secondelectro-optical element, second optically transparent output surfacethrough which the first and second groups of spectral components canexit said second electro-optical element, and second spectral-componenttransmission means, disposed between the second optically transparentinput and output surfaces of said second electro-optical element, fortransmitting the second group of spectral components of said secondperspective image to the right eye of the viewer during said firstdisplay period and transmitting the first group of spectral componentsof said second perspective image to the right eye of the viewer duringsaid second display period, while substantially blocking thetransmission of the first and second spectral components of said firstperspective image during the first and second display periods,respectively.
 4. The system of claim 3, wherein said firstspectral-component transmission means comprisesa first polarizing filterpanel for transmitting said first and second groups of spectralcomponents while imparting said first polarization state P1 to saidfirst group of spectral components, without imparting any particularpolarization state to said second group of spectral components, a secondpolarizing filter panel for transmitting said first and second groups ofspectral components while imparting said second polarization state P2 tosaid second group of spectral components, without changing thepolarization state of state of said first group of spectral components,and controllable polarization state conversion means for preserving thefirst and second polarization states P1 and P2 of the first and secondgroups of spectral components in response to a first control signalprovided to said controllable polarization conversion means during saidfirst display period, and for converting the first polarization state P1of said first group of spectral components to the second polarizationstate P2 and the second polarization state P2 of the second group ofspectral components to the first polarization state P1 in response to asecond control signal provided to said controllable polarizationconversion means during said second display period.
 5. The system ofclaim 4, wherein said second spectral-component transmission means ofsaid second electro-optical element comprisesa first polarizing filterpanel for transmitting said first and second groups of spectralcomponents while imparting said first polarization state P1 to saidfirst group of spectral components, without imparting any particularpolarization state to said second group of spectral components, a secondpolarizing filter panel for transmitting said first and second groups ofspectral components while imparting said second polarization state P2 tosaid second group of spectral components, without changing thepolarization state of state of said first group of spectral components,and controllable polarization state conversion means for preserving thefirst and second polarization states P1 and P2 of the first and secondgroups of spectral components in response to a first control signalprovided to said controllable polarization conversion means during saidfirst display period, and for converting the first polarization state P1of said first group of spectral components to the second polarizationstate P2 and the second polarization state P2 of the second group ofspectral components to the first polarization state P1 in response to asecond control signal provided to said controllable polarizationconversion means during said second display period.
 6. The system ofclaim 1, wherein said image display means comprises a liquid crystallight valve(LCLV) image projection panel, and wherein saidelectro-optical image processing apparatus comprises an electro-opticalpanel laminated to said LCLV image projection panel, and eyewear havinga first polarized lens characterized by polarization state P1 andpositionable in front of the left eye of the viewer and a secondpolarized lens characterized by polarization state P2 and positionablein front of the right eye of the viewer.
 7. The system of claim 6, whichfurther comprises a display controller for producing said first controlsignal during each said first display period, and for producing eachsaid second control signal during each said second display period. 8.The system of claim 6, wherein both said first and second controlsignals are voltage signals.
 9. The system of claim 6, wherein saidelectro-optical panel further comprisesan optically transparent inputsurface through which the first and second groups of spectral componentscan enter said electro-optical panel, an optically transparent outputsurface through which the first and second groups of spectral componentscan exit said electro-optical panel, first means, disposed between saidoptically transparent input and output surfaces, for imparting a firstpolarization state P1 to said first group of spectral components, secondmeans, disposed between said optically transparent input and outputsurfaces, for imparting a second polarization state P2 to said secondgroup of spectral components, and controllable polarization stateconversion means, disposed between said optically transparent input andoutput surfaces, for converting the first polarization state P1 of saidfirst group of spectral components to the second polarization state P2and the second polarization state P2 of the second group of spectralcomponents to the first polarization state P1 in response to a firstcontrol signal provided to said controllable polarization conversionmeans, and preserving the first and second polarization states P1 and P2of the first and second groups of spectral components in response to asecond control signal provided to said controllable polarizationconversion means.
 10. The system of claim 9, wherein said polarizationstate conversion means comprises a polarization state conversion panel,said image display panel, said first polarizing filter panel, saidsecond polarizing filter panel and said controllable polarization stateconversion panel are laminated together to form an integral unit ofsubstantially planar geometry.
 11. The system of claim 9, wherein saidfirst means comprises a first polarizing filter panel for transmittingsaid first and second groups of spectral components while imparting saidfirst polarization state P1 to said first group of spectral components,without imparting any particular polarization state to said second groupof spectral components, and wherein said second means comprises a secondpolarizing filter panel for transmitting said first and second groups ofspectral components while imparting said second polarization state P2 tosaid second group of spectral components, without changing thepolarization state of state of said first group of spectral components.12. The system of claim 10, wherein said polarization state conversionpanel comprises a half-wave phase retardation panel.
 13. The system ofclaim 10, wherein said integral unit has a maximal thickness dimensionbetween said optically transparent input and output surfaces, andwherein said maximal thickness dimension is from about 1 to about 10millimeters.
 14. The system of claim 1, wherein said image display meanscomprises an image display panel, and wherein said electro-optical imageprocessing apparatus comprises an electro-optical panel laminated tosaid image display panel, and eyewear having a first polarized lenscharacterized by polarization state P1 and positionable in front of theleft eye of the viewer and a second polarized lens characterized bypolarization state P2 and positionable in front of the right eye of theviewer.
 15. The system of claim 14, wherein the first group of spectralcomponents of said first and second perspective images include opticalwavelengths associated with the perception of the colors red and blue,and wherein the second group of spectral components of said first andsecond perspective images include optical wavelengths associated withthe perception of the color green.
 16. The system of claim 14, whereinsaid electro-optical panel further comprisesan optically transparentinput surface through which the first and second groups of spectralcomponents can enter said electro-optical panel, an opticallytransparent output surface through which the first and second groups ofspectral components can exit said electro-optical panel, first means,disposed between said optically transparent input and output surfaces,for imparting a first polarization state P1 to said first group ofspectral components, second means, disposed between said opticallytransparent input and output surfaces, for imparting a secondpolarization state P2 to said second group of spectral components, andcontrollable polarization state conversion means, disposed between saidoptically transparent input and output surfaces, for converting thefirst polarization state P1 of said first group of spectral componentsto the second polarization state P2 and the second polarization state P2of the second group of spectral components to the first polarizationstate P1 in response to a first control signal provided to saidcontrollable polarization conversion means, and preserving the first andsecond polarization states P1 and P2 of the first and second groups ofspectral components in response to a second control signal provided tosaid controllable polarization conversion means.
 17. The system of claim16, which further comprises a display controller for producing saidfirst control signal during each said first display period, and forproducing each said second control signal during each said seconddisplay period.
 18. The system of claim 16, wherein both said first andsecond control signals are voltage signals.
 19. The system of claim 16,wherein said first means comprises a first polarizing filter panel fortransmitting said first and second groups of spectral components whileimparting said first polarization state P1 to said first group ofspectral components, without imparting any particular polarization stateto said second group of spectral components, and wherein said secondmeans comprises a second polarizing filter panel for transmitting saidfirst and second groups of spectral components while imparting saidsecond polarization state P2 to said second group of spectralcomponents, without changing the polarization state of state of saidfirst group of spectral components.
 20. The system of claim 14, whereinsaid polarization state conversion panel comprises a half-wave phaseretardation panel.
 21. The system of claim 14, wherein said polarizationstate conversion means comprises a polarization state conversion panel,and wherein said image display panel, said first polarizing filterpanel, said second polarizing filter panel and said controllablepolarization state conversion panel are laminated together to formintegral unit of substantially planar geometry.
 22. The system of claim21, wherein said integral unit has a maximal thickness dimension betweensaid optically transparent input and output surfaces, and wherein saidmaximal thickness dimension is from about 1 to about 10 millimeters.